Threshold Stasis S/150

I am considering purchasing the S/150 to drive the Vandersteen 2ci. Do you think the S/150 is enough to drive the 2ci? What I have heard is that the first 30 watts is in Class A mode. Thanks 

Ag insider logo xs@2xhighend64

Might want to post/link a Phase angle and impedance graph 

along with your room size these are the pertinent points

better than should work opinions. 

The Threshold Stasis amps were among the first high current designed amps available… ~1980. I owned a Threshold s500 for nearly two decades. When I replaced it with a Pass x350 the Threshold sounded completely anemic and tinny without a real midrange. Subsequent Pass designs have improved the sound by leaps and bounds. While I loved the Threshold at the time. You couldn’t give me one. If you want sound quality fast forward a few decades.

Are you referring to room response? 

No the specifics of your speaker.

And yes most of us realize Threshold manufactured high Current amps

but thats not the question.

I believe the efficiency of those speakers is 88 db for 1 watt at 1 meter.  Not the most efficient.  I ran a Threshold Cas2 with Linn Kan II (85 db efficiency) and loved the sound.  I have to admit the Cas2 has the longest warm up period I have ever experienced.  Sounded great in 15 minutes but an hour or so in, it goes to superb.  I'm guessing the mid and high will be excellent but the bass might not be as fully driven.  I'd probably pull the trigger, especially if it was priced sweetly. 


I dont have the specifications for the 2ci since the Vandersteen does not have it available on the website. I am awaiting response.

@highend64 not validated, worth re-checking, have these notes on the Vandersteen 2CI Spec:

¾ inch aluminum dome tweeter, 4 ½ “ plastic cone midrange, 8” cone woofer, and a 10” active cone radiator that handles frequencies below 35 Hz. Fequency response is 28 Hz - 20.125 kHz at + or - 3db. Its impedance is at 7 ohms nominal and 5 ohms minimum, efficiency 88db for 1 watt at one meter.


AMP: Threshold alternative, Forte’ 1a, or Forte’ Model 3, upgraded and converted:

My Pass/Forte’ Model amp is recently reconfigured to Forte’ 1a, pure Class A 50 watts now. Voltage down, bias up. Has four new 30kuf big power caps, large Torroid transformer, new bridge rectifiers, Cardas binding posts, spade connectors removed. All soldered. Not lean at all, very musical, more grunt, 47c, runs Warm at heat sinks. It’s a giant killer now. Will drive your 2ci, no issues, all goodness :)


First make sure it was rebuilt ,this amp was built probably30  years ago and especially capacitors , dry out over time and detail and dynamics sonics lost .

ask for a build sheet rebuild, ask for pictures to see the inside .

Without That just pass how much are they asking  ?

With your system I think a parasound a23+ would be a big upgrade 

perrotta consulting you can get a good deal and free shipping 

I bought one for my 2nd audio system and just put a synergistic purple fuse on back  it sounds very respectable after 200 hours runin..

Suggesting a Parasound A/B Amp to a Threshold Class A Amp is a poor comparison! Nothing in the Parasound line is comparable, and that is from personal experience with both Amps. 


@boostedis Suggesting a Parasound A/B Amp to a Threshold Class A Amp is a poor comparison! Nothing in the Parasound line is comparable, and that is from personal experience with both Amps.


Tend to agree, argh. Had a Parasound A23+ for 45 days myself. Bought it 2nd hand from a chap who owned it a year. Plenty broken in. Was gonna use it as a backup amp. Ended up reselling it to a new owner who was okay with it. Nice build quality, nothing special about the sound in my system, just barely okay, unfortunately. Hopefully others have better luck with this unit, maybe so.

Comparing the two in my system, it’s not even close when talking upgraded/updated Class A Threshold, Forte Audio, to that particular Parasound unit. Quite a startling difference fwiw.


I am not sure if it was rebuilt but I can also get the model FET Two pre with it. I did some research notice that the S/150 models that some have the mkii. The model that the person is selling has the speaker binding post vertical where some I see was horizontal.

It’s your $$ May point was have old capacitors in it you are inviting disaster 

it’s like having 25 year old tires on your car, the dielectric and cap inside is falling apart ,especially going back 20 + years capacitor technologies was not that great.

I have been into Audio for over 40 years and have tech friends  we have literally cut capacitors apart , unless you plan on having it upgraded when you buy it then 

not such a good deal and bunches of other parts internally are on their way out 

it’s like buying a older car with 150k on the mileage , and with audio one bad part can take out several with it , been. There done that . Much better off buying new 

you didnot mention. How much $$ you were spending .it will cost you minimum of $1500 to rebuild this amp 

I understand your analogy and you make a valid point but I don’t know the condition of the amp. It could be near mint or have some wear and tear, I don’t know but that is why questions has to asked. Would you by a car that is 30 years old with 30k, probably or tires that are new from way back when , probably.

@highend64 if you buy/use one of these 30 year old amps, the main power caps and bits regularly get replaced as others have mentioned. Has to do with age, not the condition of the amp alone. Check with different techs in your area, best of luck.

Ok let me be really clear here. The Threshold amps are a great piece of history. If you want history,,, this is what you want. If you want high performance sound quality,.. what is your budget, we will help you find high end sound quality… it is not going to be a 40 year old amp.


I have not made a commitment on the amp yet. All I was asking if the Threshold was enough to drive the Vandersteen. My budget is less then 1.5k.

yes… for a speaker in production since 1977 w 250 k sold in many variants including NOW, the 2 like ALL Vandersteen products is designed to be an EASY load…no ultra low impedance dips or bizare phase angles, etc…

My brother gets excellent results w a slightly larger Threshold and the 3a-signature

Join us at Vandersteen owners forum…. lots of 2 owners can tell you what amps they use.

Do pay some attention to age of unit and VERY possible need for recap..

I'm curious about the the sound of the historical amps as they age. I enjoyed access to Woodbridge Stereo in NJ in the 1980s. They carried the Thresholds, among other goodness. I now have a possible bead on an S/500 II, in the process of a refurbishment. Or maybe a Levinson 23.5. No matter. The arc welders of yore, seventh of their names, etc. I do enjoy listening to the equipment I once coveted but could not afford.

Will an older amp exceed the original sound/detail/staging with refreshment of the older parts with more modern bits? Or is it a hit or miss proposition?

I am not at all opposed to refurb'd equipment. I feel lucky to be running a CJ 17LS2 into a Pass Aleph 5, with my Vandersteen 2ce Sigs. Both the preamp and the amp have made the journey to their respective factories and back again. If I don't try for sustained volumes above 90 dB, the setup is very satisfying. I've had multiple amps through the house and with it comes the opportunity to try "new things."

The A5 developed a hum during my stewardship, so I knew it was time. But are there other sonic cues that suggest that a solid state amp requires attention?

My dad gave me his old McIntosh gear. It's great and nostalgic and rebuilt to spec but it still sounds like 70's gear. It's great for the time period and fun to have but never want to pull out the Leben or the Pass to play the old stuff.

That said, I get what the op said about having gear from another generation can be fun. I'd rather not have primary gear that could fail. 



Your room might be too small for theses speakers. With their minimal baffles and also inherent warm, ripe sonice signature; they need space from surrounding walls. They also need space from the listening position for proper driver intergration.

Unless your seeking very high output levels, (which aren’t these speakers forte’) the Threshold S 150 should work well. The Series II versions were a nice upgrade,. later ones with the pre-Optical Bias version corrosive resistent gold plated circuit boards are worth seeking out, especially considering the age of these amps. As has been previsouly posted the original caps need replacing. Jan Soderberg an ex-Threshold tech at Vintage Amp Repair has earned an excellent reputation for updating Threshold gear. Unlike other modders whose handi-work can actually devalue gear, his work will be apprecaited and sought out. Finding a piece that has fairly recently gone through his hands might be the most long term cost effective route.

While I can’t disagree with @ghdprentice ’s perception, I think it important to remember that it is a perception. If you look through the posts here on Audiogon you’ll find some prefer the Threshold to the Pass Labs amps and visa versa. I would suggest that these earlier Thresholds are rather neutral with a very slight leaning to warmth, where as the Pass Labs are most certainly in the warmth camp. As the Vandersteen are already strongly leaning towards the warm, ripe spectrum, it might be advisable not to accentuate that with an overly warm amp.



Amongst my favoriite amps for these Vandy’s are the McCormack’s and the PSE’s. Regretably they didn’t have the robust build quality of amps like these older Thresholds and are no longer an easy reccomendation.



I still own a Threshold S350e and a Fet 10e preamp, it works just as good as it did when I bought it 30 years ago.  Funny, when I spoke to one of our repair shops regarding possibly needing recapping, he said it’s a myth. Basically said if it ain’t broke don’t fix it. He said the caps are good for many, many years and that people seem to think they need recapping every few years. Not my words but his.

FYI, the Threshold S series amps (perhaps a bit generously) were rated as outputting the first 20% of their 8 Ohm output into 8 Ohms per channel as Class A. The Class A output would halve as impedance halved, while the Class AB output would simultaneously nearly double as impedance halved.


@unsound Probably is but at a reasonable level, it shouldnt be a problem. With my room treated with basic reflective points, it made a big difference.