Next step: tube pre or tube power amp?

I own a Rotel pre/pro RSP-985 SS preamp and a matching Rotel 120 watt power amp. If I wanted to move into tubes, would I get better mileage out of a tube pre or tube power amp?

I love the convenience of the rotel preamp (remote, built in DACS etc) but I understand that a tube pre will have more impact than just a tube power amp. Is this correct?

Also, my speakers are 91db efficient. What wattage tube power amp would I need to drive them to medium/loud levels?


A tube amp will make more of a difference than you think. I went from a Carver C-1 Pre to a Cary SLP98P and thought it made a big difference. Then I went from a McIntosh 7270 SS Amp to a Cary CAD 120S Tube amp and it makes a HUGE difference. Good luck in whichever direction you move towards, I think you'll love the tube sound.
It depends on the nominal and low impedance specifications of your speakers.

If your speakers are 8 ohms nominal, and if the lowest impedance does not dip below 6 ohms, then I would suggest a tube amp will get you more than a tube preamp.

If your speakers do not fit the above profile, then a tube preamp would be the choice (but it won't deliver the sound of a tube amp).

75 watts should get the job done.
While your speaker profile will come into play, I can't quite agree with Tvad's numbers. I've been driving a pair of speakers that are 8 ohms nominal and 4 ohms minimal, 89 db sensitivity, in a fairly large room with a 80 wpc tube amp for a year now with no problems.

Tube amps will give you more *tube* flavor than a tube preamp, however, if your speakers are a difficult load, a tube preamp is the way to go. Another possibility is a good tube integrated amp.....plenty of them out there.

Thanks guys for the feedback. My speakers are GR Research AV3s in an AV2 cabinet. They are 8ohm nominal/6ohm minimal and 91db sensitive. I may one day move to the GR Research Neo2x which are the same rating, but much less sensitive - 85db.

I'd prefer a tube power amp for WAF and convenience - I can hide it behind some fake greenery in our AV cabinet...

I am also researching the Peachtree Nova - the integrated tube amp with built in DAC. A bit beyond my budget, but it looks like a great all in one package. My local Rotel dealer is also a Peachtree dealer, so I could a/b them and see what I think.

thanks for the feedback so far
09-09-09: Stevecuss
My speakers are GR Research AV3s in an AV2 cabinet. They are 8ohm nominal/6ohm minimal and 91db sensitive.

You should have no problem with a tube amp. Depending on the size of your room and the volumes at which you listen, you could probably get away with less than 75 wpc, but I'd still suggest 75 wpc minimum.
I would opt for a tubed pre amp. It will give you a hint of tube magic, and a ss amp will give you slam speed and bass impact.
Tube pre is the way to go. The load to the speakers you have is better if it comes from a SS amp.
The load to the speakers you have is better if it comes
from a SS amp.
Buconero117 (Threads | Answers)

I disagree. 8 ohm nominal impedance with a 6 ohm minimum is a reasonably
flat impedance curve which can be handled without any problem by a push
pull tube amplifier.

91dB sensitivity is a non-issue. It can be driven by either a SS or tube amp.

Frankly, IMO, the OP has his choice of SS or tube amp (provided the tube amp
is a push pull design). He may even have the opportunity to use an OTL tube
You can figure out your minimum power needs by remembering that you double the power for each 3db gain in loudness. So the 91db sensitivity at one watt needs 2 watts for 94, 4 for 97db and so fourth. This gives the MINIMUM required, which is not necessarily the ideal power but is a rough guide. I doubt if you would need 75 with your current speakers but if you intend to change it can't hurt to get a larger amp as long as it is of the same quality.
Keep in mind the power required for dynamic peaks in music. An "average" listening volume of 91dB can reach 100+dB peaks pretty easily. At a 107dB peak on 91dB speakers, the amp is putting out 64 wpc, and the requirement jumps to 128 wpc for a 110dB peak.

Also keep in mind the sensitivity number is measured 1 meter from the speaker drivers. So, 91dB measured from a listening position in a medium to large room will translate to a higher measurement at 1 meter from the drivers.

In my medium size room, it's pretty easy to approach a decibel level that requires 60wpc from the amps.
09-09-09: Stevecuss
I'd prefer a tube power amp for WAF and convenience - I can hide it behind some fake greenery in our AV cabinet...

Tube amps that I've owned throw out more heat than any Class A SS amp I've owned. So you may not be able to hide a tube amp in your A/V cabinet. Just something else to think about.....
Hi Jmcgrogan2,

thanks for that input and I'd considered heat. Our AV cabinet is open - a cutout in the wall of the house, essentially, so it has plenty of ventilation above and around it. I use a fake green planty thingy in front to cover the front of it. Who knows, maybe my wife will love the glow of tubes...
I would go for a tubed preamp first, although a tubed power amp would be a natural step forward in time.

There are good options in the used market from Melos (SHA1 sig), Audible Illusions or Counterpoint.
I have just seen an Aranov preamp here at AGON that looks like what you are looking for...(I do not know the seller and/or interested in pushing this item) just a safe disclaimer. :)
For your situation I support the suggestion for the tube amp. I've tried all SS/tube pre/amp combinations, and my favorite was the SS pre/tube amp combo I had until a few years ago. I observed a bigger change in the sound (for the better) with the tube amp than anything else. I intend to move back to a tube amp soon for that reason. And your speaker's specs suggest that a reasonably priced tube amp should be able to drive them with authority. I think you'll be thrilled with the tube amp and Rotel preamp.

Stevecuss, I owned the Rotel 980BX amp & RC990BX preamp a long while back w/ B&W speakers for a short time. Rotel delivers a lot for the money, but their gear is extremely lean compared to other manufacturers(B&W's didn't help). I just felt that the life was bleached out of music. The move to tubes was the best thing I ever did.

That being said, I always felt that the Rotel amp was far more neutral than the preamp, sonically.
If you choose a tube amp, then, as Tvad said, you have to pay attention to the impedance curve of your speakers, assuming you want a reasonable frequency response.

A tube preamp will likely mate OK with your Rotel amp. This option will probably be less problematic than a tube amp.
One more time, a tube pre will give you the advantage of tubes without the heat and cost of a tube power. BUT, tube pre's aren't cheap. At least, get a tube DAC if CD's are your main source of input.
ive owned tubed pre's with SS amps and tubed amps with SS pre's, and even tube cdp's. IME, tube amps are the way to go for truly 'tubed' sound.
09-12-09: Jw94055
One more time, a tube pre will give you the advantage of tubes without the heat and cost of a tube power.

One more time, a tube pre is a good starting point and will give you some tube flavor. A tube amp will provide more tube sonic traits. It all depends how far you are willing to go, and for some, it is the wrong direction.

A tube pre is the best start. Tube power amps are hot and expensive. In order to get the best out of a tube amp you will need to roll tubes, and that can get quite expensive.
Orpheus10, I don't disagree that a tube preamp may be the best way to start, to see if one likes the tube sound.

However, your second statement makes no sense to me. One could say the exact same thing about a tube preamp, that to get the best out of it you will need to roll tubes......that also can get quite expensive, in many cases more expensive than rolling power tubes.

My preamp tubes are more expensive than my amp tubes, because I notice that rolling preamp tubes makes more of a sonic difference than rolling amp tubes.
I agree with John that the cost of preamp tubes could be more expensive than the cost of power amp tubes. My experience has been that there are some really excellent current production power amp tubes, whereas current production small signal tubes are not nearly as good, therefore requiring NOS small signal tubes for a component to sound its best.

I still disagree that a tube preamp is the best way to start to get tube sound. IMO, it's a compromise that only gets you half way there.
I will have to also agree with Tvad's post;It has been my experience that going the pre amp route will only give you a peek into the tube world.
If you really want the whole experience I would go with tube
power amps(s);as far as the last part of your question of power with 91 db speakers I would think you would not need massive amounts of power however; I think the answer to this question is more of a personal choice; remember you may not keep those speakers forever and having a higher powered amp may give you more options when the time comes.
Hi Folks,

thanks again for all your feedback and I know the world of tubes is both complex and opinionated. I'm a guitarist and a tube snob when it comes to guitar tone, so I assume I'd also prefer tube sound in my listening. For guitar, there is simply no comparison.

But, budget remains the primary constraint and I'll be easing my way in. My primary source is hard drive, so a good DAC will be key. I'm also going to look into integrated tube amps as an alternative. Some of the Jolidas get good reviews as does the new Peachtree Nova. I don't think I'll have the budget for full tube separates at this point, so this may ne a good next step.

Also, I'm fortunate to live in Denver, so I'll be at RMAF next month and should get tons of good info then.
Check out the used Mesa Baron just listed for sale.

No affiliation with the seller.
You could always try a nice tube integrated. That will allow you to see if you like the tube sound.

I am currently using a will vincent modded dynaco st70 and classe dr6 preamp (said to be somewhat tubelike) and love the combo.

I also have a bryston 3b st amp, but I prefer the soundstage and musicality the dynaco provides.

I did not like my dynaco much with a set of inexpensive el 34 tubes but after a switch to genelex kt66 repops it sounds great.( It is fun to tube roll and change the sound of your gear)

If you go amp or preamp I would go amp first with a kt88, or 6550 based power tube. Those tubes will give you a hint of the tube sound without being too "warm".
Hi Folks,

I like the idea of a tube integrated and I'm looking at the Jolida 302b - looks like a great entry level tube amp and its quite modifiable. I'll also look at some of the other chinese outfits - ming da and Cayin etc and start saving my pennies.

best wishes

Steve - I had an Acoustic Plan SItar (hybrid integrated) a nice option to get the best from both worlds, Pathos has also some interesting options in that route.
Another alternative could be a hybrid amp and a tube preamp.
Stevecuss: If you are now liking the idea of a tube integrated, I recommend you add Leben to your audition list. A SS integrated option that has a lot of "tube-like" sonic/musical character would be Luxman. Both are exceptional!
Stevecuss, since your source is a hard drive then you don't really need an integrated since your DAC will provide plenty of output (although you should probably keep the interconnect cables short). Plus your speakers are an easy load for almost any tube amp.

We offer a well-known amp called the M-60 that would drive these speakers easily, and we have a volume control option for it.

IOW, all you seem to need is a power amp that has volume controls at its input- might be a simpler way of doing things. If you add more inputs later, then a preamp would be a good idea.
I cannot believe that this whole discussion went by without anybody asking his room size, the kind of music he listens to and how loud? Those were the major considerations for me when I decided I wanted to go back to separates. For example, I have a 28x15x7 room, I like orchestral/organ music and I sometimes like it loud. For me to add tube power amps, we would be talking something along the lines of VTL Wotans (or the like), which are very expensive.

I bought an Audible Illusions 3. Hooked it up to my Pioneer receiver pre in/out circuit, which disconnected everything but the power amp section, and used the Modulus as a control amp. Never looked back. Also a preamp is not really speaker sensitive while a power amp is and must be matched to your speakers. Now I have Quickies V4's and the AI M3A. Just my 2 cents.
10-20-09: Drjjpdc
I cannot believe that this whole discussion went by without anybody asking his room size, the kind of music he listens to and how loud?
While the questions were not asked directly, the issues were touched on in several posts, and there doesn't seem to be any complaint from the OP about the advice offered thus far.
I'm very happy with the response so far, but to answer your questions, my room size is 15 by 25 or so (open family room/kitchen layout) and is highly compromised by non musical needs. Currently, the best listening position for the music is while washing dishes, which no doubt makes my wife happy (ie, it motivates me to wash dishes....)

My favorite music is acoustic based (Allison Kraus, Nickel Creek, Buddy Miller and Lyle Lovett would be my top 4) and good rock and blues comes in second, but I have a broad palette - jazz, classical, broadway etc all work as well.

As a DIYer, I'm exploring buying an old Dynaco ST70 and restoring/modding it. Alternatively, I heard the new Jolida FX series of tube integrated amps and was very impressed for their $450 price tag.

best wishes
I bought a tube processor from Grant's Fidelity in Calgary ALberta.

It solved my obsession with acquiring the perfect sound, now my kit sounds 'good enough for the girls I go with'and even good enough for me

And now, I can happily surf the sites, without lusting after the latest, greatest, tubiest or whatever