Soundlab speakers with sub woofers?


Hello, I'm looking for input from folks that have used Soundlab speakers or electrostat speakers with sub woofers. It's thought that the sub woofer needs to be quick in order to keep up with the speed of the panel and integrate seamlessly. Has anyone found a subwoofer(s)that was fast enough to work with an electrostat panel and more specifically Soundlab electrostats? What model of subwoofer worked well and how was the subwoofer integrated into the system?
keithmundy
If you can find them, a pair of Kinergetics SW-800 subs and an 800c xover was a very popular option for panels like the Martin Logan CLS's. If not, the Vandersteen subs would probably be a good match, as well. That said, have you heard the Soundlab's? They may not need subs.
Hello Zd542, yes I have heard the Soundlabs and they can have good bass. I'm just worried about optimizing the bass because I have a limited amount of room to move the speakers. I'm just trying to think ahead. I may even have to use some sort of EQ. I'm very picky about the bass and I'm just trying to get info from others that may have worked through this process already. Thank you for responding.
"I'm very picky about the bass and I'm just trying to get info from others that may have worked through this process already."

Hopefully, you can avoid having to get an EQ. Since you're trying to plan ahead, I think your choice of amp may make that difference. I don't know your personal tastes, but almost every time that I've heard Soundlab's was with Boulder electronics.
A few years back I heard an A1 system with Soundlab's subs, don't remember the model name but the sound was extremely impressive and musical. Don't know if they're still making them but its worth looking for a pair of their low frequency panels.

david
David, thank you. I didn't know that SL made subs. I will check that out. Thank you for responding
Keith - If you have a limited amount of room available to position the speakers, dipolar designs like the Soundlabs may not be the best speaker for your application. Their positioning doesn't just affect the bass, but the overall performance level of the speaker. If there's any way that you could try them in your room before purchasing it would be advisable and could save you a lot in the long run.
You're welcome Keith. They had 2 or 3 different electrostatic subs, the large one matching the A1 was the B1 and its fantastic. In all honesty A1+B1 would be my choice speaker system if I could use the Lamm SETs with them and I didn't have the Bionors.

david
Bill_k, Yes, I agree about trying them out first. I spoke with Roger West (Mr. SL) about that and he said that he would be happy to send a pair out for me to try in my room. He said in his 30 years no one has sent them back!

Dkarmeli - I'm going to shoot Roger at SL an email tomorrow to inquire about the subs. He has always been very helpful. It's just nice to get real world advice from end users too. Thanks for your help.
Good luck Keith!
david
It's thought that the sub woofer needs to be quick in order to keep up with the speed of the panel and integrate seamlessly.
What's the basis for this thinking? Why does speed tend to be brought up when people talk about subwoofers? Why is it thought that panels are somehow faster than conventional cone drivers?

Martin Logan makes subwoofers, so that may be an option for you. I think that your room, placement options and other electronics in your system will have a greater impact on how well any sub integrates than any specific sub you choose.
Bob - well I always hear that one needs to make sure and have a sub that is fast enough for a panel. Obviously a panel doesn't move very far and woofers move quite a bit so.... I suppose that there is some trick into getting them to integrate smoothly? Not sure, just inquiring. Yes, obviously the amps etc... will definitely play a big role, but when it comes to bass the room appears to be a big part of that puzzle. Moving the speakers seems to be the first option, then treatments, then EQ and/or subs is the way I have come to understand it. Thanks for your response Bob.
"What's the basis for this thinking? Why does speed tend to be brought up when people talk about subwoofers?"

Its not so much speed as it is control. Subs need a lot of power, and if you don't have it the bass loses definition. You get that one note booming type of sound like you find in a HT sub. So when you move away from that sound to a more detailed one like you need for music,the sub sounds faster because its better able to integrate with the other speakers. There's other factors as well, but this is probably the most important issue.

Vandersteen does a really good job explaining all different factors that go into making a sub. If you go to their website you can download owners manuals. Read through a sub manual for a better explanation.
The right amp is what makes for bass on a Sound Lab. Generally speaking, transistors are not a good match. The reason is the Sound Lab, like most other ESLs, has a 10:1 change in impedance over its range, and is over 30 ohms in the bass, making it hard for transistor amps to make power, and it does need the power.

So if you have a transistor amplifier of 600 watts, it will make about 150 watts in the bass region, which means a 150 watt tube amp will be able to keep up with it no problem.

Set up correctly I've heard these speakers shake the walls and I do wonder if a sub is needed, since they can go to 20Hz all by themselves!
I was just poking fun... The speed myth regarding subwoofers is generally just that -- a myth. Group delay could be poor enough to be audible and would sound slow, but I can't recall any sub whose measurements show a group delay greater than one cycle. I don't buy the generalization about "HT" subs. I don't buy the generalization that a multiple driver sub is automatically better than a single driver sub.

Any subwoofer from a reputable manufacturer will likely be sufficient for either movies or music. The critical issue in either situation is the setup - not the specific sub or design - and sizing that meets the desired SPL in your room.

In many cases music places less demands on a sub than movies so a smaller unit can be used in a music only system. Even so, since bass drivers are distortion generators (20% - 30% range is not uncommon) choosing a single high performance sub or multiple lesser subs could be justified.

And, yes, the room is THE problem for bass frequencies. Placement options is a key advantage of using sub(s) versus main speakers to reproduce bass. And though many purists poo-poo it some form of equalization can be of benefit.
Check out Larry Greenhill's subwoofer reviews on the Stereophile website. He uses Quad ESL main speakers.

http://www.stereophile.com/content/velodyne-digital-drive-plus-18-subwoofer
http://www.stereophile.com/content/bowers-amp-wilkins-db1-subwoofer
http://www.stereophile.com/subwoofers/jl_audio_fathom_f212_powered_subwoofer/index.html
http://www.stereophile.com/subwoofers/808svs/index.html
http://www.stereophile.com/subwoofers/907jl/index.html

I use a pair of Hsu Research ULS-15 subs in my system and would not hesitate to recommend them.
"10-29-14: Atmasphere
The right amp is what makes for bass on a Sound Lab. Generally speaking, transistors are not a good match. The reason is the Sound Lab, like most other ESLs, has a 10:1 change in impedance over its range, and is over 30 ohms in the bass, making it hard for transistor amps to make power, and it does need the power."

Every time I heard Soundlab speakers it was with SS amps. Even at CES, Soundlab used SS amps in their own room.
Atmasphere, I've read that comment about SS amps and electrostatic speakers many times (and I know this topic has been discussed countless times here) and it still doesn't make sense to me.

In my feeble mind I imagine a relatively fixed voltage across the speaker terminals. As the impedance changes with frequency so will the current drawn from the amp and so will the power supplied by the amp. When the impedance rises in the bass, the current drawn from the amp will decrease as will the power supplied by the amp. Likewise when the impedance decreases in the midrange and treble, the current drawn from the amp will increase as will the power supplied by the amp. I think that's based on Ohm's law.

It seems to me that the only thing that matters, regardless of the type of amplifier, is that the amplitude vs frequency curve is reasonably flat across the audio band. It seems like you're implying that that isn't the case with SS amps.

I apologize in advance to Keith for going down this detour.
I'm sorry Bob_reynolds but none of subs you suggested come even close to Soundlab's B1 or B1S. None of them will properly integrate with Soundlab panels, they don't have the resolution and you're stuck with their crappy built in amps. Once you get into Soundlab level speakers you need the rest of your system to match accordingly. If you use Tube amps on the panel then that's what you need for the sub or you stay all SS of the same quality, preferably the same amp for the subs. IME these powered woofers will do for HT sound effects but they don't have the quality for high end music reproduction.
david
Thank you all for the responses. Yes, I agree SL does have pretty darn good bass. I'm just worried if I might need to use other subs to get the bass optimized because I will not be able to move the panels around which appears to be the usually the way the bass is optimized with the SL
Keith, subs aren't woofer towers, they're the to enhance the low and very low frequencies, you can't use them for easing speaker placement.
david
Keith, subs aren't woofer towers, they're there to enhance the low and very
low frequencies, you can't use them for easing speaker placement. Subs will
add to the complexity, they have their own placement and setup requirements
that must be taken into consideration.

If you're worried about your room and buying them new, you should make
some kind of deal for setting them up with your dealer.
david
The question of panel vs dynamic subs mating well with panel speakers is probably not worth debating unless you've heard both types in a similar environment. Outside of Soundlab's own Roger West, I can't imagine that too many folks have actually experienced this because (judging from the photos here):

http://www.soundlab-speakers.com/customer-installation.html

you'd have to be an unusually dedicated (read "crazy") hobbyist to set up Soundlab's subwoofers and then send them back. In the words of Eddie Murphy regarding suitcases (IIRC) those suckers are with you for life.

PS - FWIW, my own experience is that mating dynamic subs with Magnepan panels is much less daunting than many believe, provided you have the tools for the job. IME it's certainly a lot easier in the digital domain, if that's appropriate for your needs.
BTW, Soundlab's FAQ section essentially mirrors Bob's view that the speakers' high impedance in the bass is SS friendly due to the reduced current demand. OTOH, taking that position is certainly in Soundlab's own interest since it allows them to suggest that their speakers pair well with a wider range of amps.
It's not a question of technology of the subwoofer but the it's quality! There are very very few of them that have a place in a high end system irrespective of design tech. For me a digital crossover is the death of any system with high end aspirations.
david
David, No need for you to be sorry. I respect your opinion about Soundlab's products, but there's no solid evidence to support it. That's the norm in this hobby.
Best regards,
Bob

BTW, the only sub I suggested was the Hsu ULS-15 that I currently use. The links to the Stereophile reviews were those that were done with panel speakers and I thought would be relevant to Keith.
Keith, you might want to reach out to Duke Lejeune. He has experience with Soundlab, understands small room acoustics and builds speakers (including subs). I'm sure you'll get solid advice without the hype.

http://www.audiokinesis.com/
That's funny that you mention Duke.... I did just talk with him the other day - great guy. And yes, he does have a great deal of experience with SL and he makes a set of subwoofers called The Swarm that he says works well with SL. There are a total of four sub woofers in The Swarm. I need to talk with him further, but with his experience I'm sure The Swarm would probably work great. Not sure the cost though.
My Soundlab M1PX's driven by CAT JL3 monoblocks (150 watts/ch)have very musical, spectacular bass. No subwoofer needed here!

In fact, when auditioning CAT JL1 tube monoblocks (100 watt/ch.) several years ago against my Mark Levinson 350 watt/ch. ss amp, the CAT’s increased control and drive in the bass region was the immediate positive sonic attribute that I noticed. In that realm, the CAT's did an absolute sonic tap dance on the Levinson! After a few more minutes and absolute disbelief of what I was hearing, I realized that the CAT's enhanced not just the bass, but the entire audio spectrum including the sound floor, harmonics and the note's leading and trailing edges! The differences were so stark, that immediately upon firing up the CAT's, NO thought was given to keeping my Levinson.

Thus, at least with CAT (tubes) vs Levinson (ss), I couldn't agree more with Atmasphere's comments regarding tubes and Soundlabs.

Atmasphere: The right amp is what makes for bass on a Sound Lab. Generally speaking, transistors are not a good match.

In fact, I recently was able to hear Ralph's, Atma-sphere amps (MA1's and MA2's) with Soundlab's. The result was very impressive. I was at an audio dealer's, not my home, so I really couldn't compare Atma-sphere's sound with my CAT's. But what I heard was more similar than different, and sounded just wonderful; so, much so, that I wouldn't hesitate to use Atma-Sphere's (tubes) with my Soundlabs.

If you're thinking of trying/buying Soundlab's, being worried about needing a subwoofer, would be the least of my concerns. IMHO, Soundlab's electrostatic bass is a huge positive and simply must be heard.

While I have no need to reproduce movie sound effects in my 2-channel only room, the canon explosions on Telarc's 1812 Overture are reproduced tightly and with authority and bass riffs (electric and standup) are simply outstanding. I can't imagine needing more!

With that said, I 2nd., soliciting -- frequent Audiogon contributor -- Duke Lejeune's input. As a Soundlab dealer and audio speaker and instrument bass cabinet builder http://www.audiocircle.com/index.php?topic=125121.msg1319009#msg1319009, he is in a perfect positon to provide uniquely experienced advice.
Two JL Audio Fathom 112 or 113's depending on your room size. If you have the room to setup the Soundlabs and have room for two subwoofers. The key to getting any sub to sound good is proper placement within the room. It also requires time to find the correct crossover point and slope. I am a former REL subwoofer owner used with at that time Martin Logan Odyssey's.
Mrmb when you were listening with the ma1 and ma2; did you hear a difference that would justify the extra cost of the ma2 over the ma1.
I am a owner of M2's with tordial upgrade and impedance mods and was just curious about how the 2 of these amps compared.
Wow! Has anybody else been unable to log it to the forums for days!? I've been wanting to respond to the forum but have been unable to get in. Anyway... Statman - how did you incorporate the subs with the crossover point? I assume one sends a full signal from the preamp to the sub and then the crossover point is implemented at the sub? Thanks. I'm currently running Pass Labs XA160.5's but I'm thinking that I may go with the Pass 600.8 if I run the Soundlabs. I have never been a fan of the Atma-sphere amps, but I've never heard them with the SL speakers.
Rleff: Hearing the MA1 and then the MA2 with Soundlab U1PX's was a real treat. As could be imagined, the overall sound was very, very similar. The MA2's had a little more gravitas -- i.e., control and thus, refinement. The difference was minimal & as such, wouldn't be noticed without A/B'ing them back to back. Would I have been able to blindly discern the difference? I really can't say, which to me, suggests how close they really were.

Of course the speakers were "PX's with the new consummate upgrade. Hence, they present a more benign load than they formerly did. I would imagine that the non-PX panel and previous generation toroidal transformer speakers would benefit more from the higher power MA2's.

If dollars weren't an issue & I hadn't heard the MA2's, I could be quite happy with the MA1's. I must admit however that the comparison wasn't lengthy, nor with overly complex material. If I had both amps in my system and had several days to compare, the differences may have been more pronounced, but then again maybe not.

Certainly with new Soundlab PX panels and backplate electronics, one needn't be concerned with the MA1's driving ability. Then and only then if that last few percentage points of refinement were appreciated & the extra funds and heat weren't a concern, then MA2's may be just the ticket....
In my feeble mind I imagine a relatively fixed voltage across the speaker terminals. As the impedance changes with frequency so will the current drawn from the amp and so will the power supplied by the amp. When the impedance rises in the bass, the current drawn from the amp will decrease as will the power supplied by the amp. Likewise when the impedance decreases in the midrange and treble, the current drawn from the amp will increase as will the power supplied by the amp. I think that's based on Ohm's law.

Hi Bob- your statement here is correct. So the impedance curve of the Sound Lab goes up to just over 30 ohms in the bass, and is about 1.5-3 ohms at 20KHz depending on the setting of the Brilliance control.

So let's do the math. We will assume a constant voltage, and for fun a 600 watt transistor amplifier driving 8 ohms.

Power = Current (I) x Resistance squared. So we need to solve for current.

600 = I x 64, 600/64= 9.375 is the current of 600 watts into 8 ohms. Using Ohms law: 8 Ohms =V/9.375 Amps, we see that the voltage is 75 volts.

Now we change the Resistance to 30 ohms, keeping the voltage constant. So: 30=75/I, solving for I we get 2.5 Amps.

Power is Voltage x Current, in this case the 600 watts is now 187 watts.

At the other end of the frequency range, the amp can put out over 1200 watts, as there is a 10:1 difference in impedance.

Basically what the math shows is that a 600 watt amp can't make that kind of power- and so a 150 watt tube amp can easily keep up with it, as the difference between 150 and 187 watts is not even 1db. If you have a 200-watt tube amp, you would need a transistor amp with about 800 watts in order to keep up.

The math also shows that there is a good chance that the transistor amplifier will be bright on the Sound Lab.

Now the application of negative feedback will cause the amplifier to reign in its power somewhat at higher frequencies. But since the feedback voltage is really not correct on this load, there will be an error that causes the amp to make too much power at the higher frequencies. Its is easily audible.

Now the speaker curve is not based on a driver in a box as we all know. Its based on a capacitor. Its efficiency is thus not a function of its impedance- its about the same at high frequencies as it is at low frequencies. You can see that a constant voltage characteristic in the amplifier is not really all that desirable. You can read more about this phenomena at this link:

http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php
Atmasphere, thanks for the reply. I follow your arithmetic, but not your conclusion.

You contrived an example whereby the specified power of an amp was necessary to achieve the desired SPL into 8 ohms and then showed that the required power to achieve that SPL is much less in the bass region and much higher in the treble region. That's fine, but what's your point?

I have no idea what the SPL would be from a Soundlab speaker driven at 75 volts, but if that's what's desired, then it's going to take a lot of power to make it in the treble. I don't see how the characteristics of the amp can have any impact on the characteristics of the load. If you need a certain SPL and it takes a certain voltage to produce that SPL, then the power necessary is whatever it turns out to be.

As I said, regardless of the type of amplifier, the only important fact to me is that frequency response is reasonably flat at an SPL that fits my needs.

Again, thanks for your reply.
I thought I was pretty clear with my point, but maybe not. Here it is, referring to the math I posted earlier:

1) many solid state amps will not get flat frequency response- if so they will be bass shy and too bright.

Some people with transistor amps have the speaker placed closer to the rear wall than is ideal; in this way they get some bas reinforcement, but its usually a 'one note' sort of bass as the reinforcement from the wall only happens at one frequency. The speaker should be 5-6 feet from the wall for best results.

2) A solid state amp will manifest approximately 1/4 of its rated 8 ohm power specification.

Its not voltage that drives a Sound Lab. Its power. That is why I provided the link at the end of my last post.
Keithmundy,

That is exactly how I have them running. I'm using Transparent Audio super interconnects balanced signal from the pre to the subs crossed over at 40HZ. You can only sense they are on if the music has definite bottom end. It's amazing on well recorded pieces.
Atmasphere,

I've read many of your posts, as well as, the info on your web site. I'm sure it's clear in your mind, but it doesn't translate to the written word for me.

1) There was nothing that I could tell from your example that was relevant to frequency response, other than you simply making a statement.

2) I have no clue what you're saying.

Its not voltage that drives a Sound Lab. Its power.
For any given resistance, power dissipated by that resistance is directly proportional to the voltage across it. As I adjust the volume level on my preamp I directly adjust the voltage level across the speaker terminals. Depending on the frequency of the signal, the power dissipated by the speaker will be determined by the resistance at that frequency. Assuming we don't exceed the limits of the amp, the voltage across the speaker terminals should be the same throughout the audio band. The power dissipated by the speaker will fluctuate throughout the audio band inversely proportional to the impedance. I don't see how the type of amp can have any impact on this.
Understanding your speakers will help when you try to tune subwoofers, whatever the brand, to aid the bass.

The Soundlabs, as well as any other stat or dipole that runs down into the bass, will exhibit reinforcement at some frequencies (constructive interference), cancellation at other frequencies (destructive interference), phase shift (various degrees at all lower frequencies), and there is absolutely no way around those realities of physics. Folks are prone to saying "but oh, you have to hear my system, I have no problems" but that is simply wishful thinking. As long as folks will tend to define themselves by their possessions the "mine is perfect" syndrome will rear its ugly head. But the compromises, fairly big ones, are there at the lower frequencies.

Most folks don't want to use a high pass filter on such a large speaker that is capable of low frequency output(and this is the fatal trap, the ability of putting out low frequency energy, lulling folks into wanting to use it, but this is different than putting out relatively flat, somewhat low distortion low frequencies, which no full range stat can do) but blending will be more difficult if one lets the Soundlab run down low. No matter what the sub, it cannot track the uneven bass of a stat and fill in where needed. Most folks have blamed subs for being "slow" when problems arise when blending a sub, but in reality even a perfect sub will make the problem worse when it is overlapping in frequency coverage with the stats.

By the way, there is no "slow" sub and no "fast" sub. The erroneous terms "fast" and "slow" have arisen when folks have tried to describe the sound of subs that have low ("fast" sounding) or high ("slow sounding) harmonic distortion, or when a low distortion sub overlaps the frequency range of a monitor speaker, creating excess bass at certain freguencies.

If you do not want to put a high pass crossover in front of the Soundlabs you do have an uphill battle. That is not to say that you cannot achieve better results than you have now, but there will be no "MAGIC BULLET". Your best bet will be to obtain the lowest distortion sub you can that also has a variable crossover point as well as the ability to change the low pass slope.

The JL models previously mentioned are an example of good subs that have good adjustability. But they do not come with a high pass crossover for your speakers, should you want to try that route. They do have a new crossover that is sold separately but I cannot speak first hand of the quality.

Remember, it is not possible to beat physics, and if it were there would have been plenty of full range panel speakers with great bass over the years. The Martin Logan CLS, the Apogees, the Soundlabs, and we could go on and on, all had their problems in the bass. The only stats that don't have real, apparent non-linearities in the bass are those that have little bass to begin with so the problems are not as easily noticed. Those are also the ones that are easiest to blend subs with....and it sound here like I am advocating a simple high pass filter on Soundlabs. I am, despite the seeming paradox of having a big speaker and not using the bass from it.

Hi Bob, You got it almost completely right in your last paragraph- right up to the last sentence... so, you said

The power dissipated by the speaker will fluctuate throughout the audio band inversely proportional to the impedance.

Which is correct. Now all you have to do is understand that the efficiency of the speaker does not also change- it is the nearly the same at all frequencies.

The Sound Lab has an impedance curve that varies by about 10:1 from bass to ultrasonic (30 ohms down to 3 ohms or less). So if the amp makes more power than it should in the highs and less than it should in the bass, it can't help but to impart a coloration.
Mrmb heard the MA-1s and MA-2s here on the U-1PXs several months ago in our large custom designed, acoustically symmetric room. Since that time the speaker positioning has been improved, yielding better imaging and mid bass, along with a significant evolutionary improvement in the DAC he heard.

Brian Walsh
Atmasphere,
Now all you have to do is understand that the efficiency of the speaker does not also change- it is the nearly the same at all frequencies.
That makes sense. So as long as the voltage across the speaker remains constant the SPL will be nearly the same at all frequencies, which would yield a nearly flat frequency response.
So if the amp makes more power than it should in the highs and less than it should in the bass, it can't help but to impart a coloration.
How can an amp produce more power than what is being dissipated by the speaker? The speaker's impedance (in conjunction with the voltage across the speaker) determines the current drawn from the amp and thus, the power that would be produced by the amp. The amp will produce only as much power as the speaker requires.

The only coloration I can see caused by an amp would be a tube design with a high output impedance. In that case the frequency response mimics the impedance curve of the speaker. So a tube amp driving a Sound Lab speaker will boost the bass and roll off the treble relative to the midrange.
Bob, part of the disconnect here between you and Ralph is due to terminology. Including:

1)Strictly speaking, speaker efficiency refers to acoustic power out vs. electrical power in. It is also commonly used to refer to SPL at a given distance vs. electrical power in. SPL vs. voltage in is sensitivity, not efficiency.

2)When Ralph says that an amp "makes power," he is referring to how much power the amp delivers to the speaker.

3)When Ralph says that a Sound Lab is driven by power, not voltage, he is asserting that for the speaker to produce flat frequency response in its acoustic output, it must receive electrical power (not voltage) at its input that either is or approximates or approaches being flat as a function of frequency.

As you realize, given the huge decrease in the speaker's impedance between the bass region and the upper treble region, no. 3 can only occur if the voltage at the amplifier output terminals/speaker input terminals is NOT flat as a function of frequency.

Also as you realize, nearly all solid state amps will produce output voltages into varying load impedances that are essentially flat as a function of frequency, as long as the amp is operated within the limits of its maximum voltage, current, power, and thermal capabilities.

While on the other hand the interaction of the output impedance of a tube amp and the variation of a speaker's impedance as a function of frequency will result in nearly all tube amps coming at least a little bit closer to supplying power (not voltage) into a varying load that is flat as a function of frequency, when the amp is operated within its capabilities.

Also, the MAXIMUM power capability of a solid state amp into high impedances can generally be expected to decrease in close proportion to the impedance rise above 8 ohms. While that decrease will usually occur to a considerably lesser extent with tube amps, and an increase may actually occur with some amps over some range of impedance increase. Ralph is correct that a solid state amp rated at 600 watts into 8 ohms will generally be able to deliver only about 150 watts into 32 ohms.

Best regards,
-- Al
"Also, the MAXIMUM power capability of a solid state amp into high impedances can generally be expected to decrease in close proportion to the impedance rise above 8 ohms. While that decrease will usually occur to a considerably lesser extent with tube amps, and an increase may actually occur with some amps over some range of impedance increase. Ralph is correct that a solid state amp rated at 600 watts into 8 ohms will generally be able to deliver only about 150 watts into 32 ohms."

Looking at the above example, is it correct to assume that if the amp has no trouble driving the 600 watts into 8 ohms, it will have no trouble driving higher resistance with less watts, like 150 watts at 32 ohms? The logic being that even though the amp is not producing as much power, the higher resistance makes it easier for the amp to handle. Discussion on this topic doesn't come up too often, where as there's plenty of talk on the other end of this; needing a more powerful amp to drive low resistance loads. I've always assumed that if an amp is OK driving a load at a given resistance, like 8 ohms, it will have no problems with loads of a higher resistance.
ZD, yes, that all sounds right to me, with respect to the sonic performance of the solid state amp in itself. That is a separate issue, of course, from the question of how suitable the amp may be for use with a speaker which doesn't want to see constant voltage as a function of variations in load impedance.

Also, although you are referring to solid state amps, I'll add that in the case of tube amps having output transformers a caveat might be that if there is a substantial mismatch between load impedance and the impedance the output transformer tap being used is designed to work into, there may be a significant increase in distortion (as well as a reduction in maximum power capability, relative to what it would be if that match were optimal). Ralph can most likely provide a better quantitative perspective on that than I can.

Best regards,
-- Al
On most tube amplifiers its a good idea to try the Sound Lab on the various taps of the output transformer to see which works best.

Some transformers can ring if not properly loaded- so if you are on the 8 ohm tap and the amp is playing into a 30 ohm load on a bass note, you may get increased distortion (lower ordered harmonics) that might cause the amp to sound warmer than is actually correct. It depends on the design of the amp as to whether there will be a significant loss of power with such a mismatch, but IME usually the loss of power is slight. If the amp has negative feedback most of the distortion will be controlled but that can be a double edged sword as with more feedback comes a greater tendency to behave as a voltage source.

With our MA-2 (about 70% of our production in the last 20 years are driving Sound Labs) there is also a slight loss of power into 30 ohms (about 10 watts), but distortion is actually reduced into the higher impedances.

In short, this is a speaker that benefits more than many box designs from a slightly higher output impedance in the amplifier.
I heard a pair of Soundlab Ultimate 1's driven by a pair of CAT mono block amps in a fairly large room of an audio friend.

Absolutely no need for one or more subs.

I have owned several other stats, and even tried the ML Depth sub with CLS11z when I had them.

I preferred the CLS without the sub.
Less bass wallop, but also a more unified sound.

When I ran a full out HT set up with two pair of CLS and the Theatre centre channel the Depth came into it's own on the .1 end of things.

I also had two Velodyne ULD 12 on a pair of Quad 63, that added more bass but again you gain in some areas and lose in others.

If your stats go down to the mid 30's as the ones I have now do(Acoustat 3, servo amped)I don't think you will need to add a sub.
Hi just came across this post today.
 I am using janszen zA2.1 with a Sumo Delilah X-over (no EQ, internal switch set to use external x-over) and SoundLab A-3s and KLH Model Nines. The Nines are faster than A-3s and mesh extremely well with the superb dual 7" woofers in the zA2.1. In my opinion the Nines sound better than the A-3s