How many tube watts for Vandersteen 2's?

In an 8 x 12 room for jazz, female vocalists at moderate volumes how many watts? Is a VTL IT-85 enough, I'm using a YBA Integre right now and it seems okay but I would like to try tubes
I know a gentleman acquittance that uses them with a pair of quicksilver mono amps. The sound is really open and very dynamic for such a low power amp. I would think the VTL would work very well in that size room.
I used a Audio Research Classic 60 with my 2Ci a few years back with absolutely no problems. Given the size of your room any tube amp over 35 watts with a good power supply should work. Obviously more is better, but it's a starting point if funds are an issue.
Believe it or not, the best I've heard Vandersteen 2s (and I've heard them a lot) was with a 35 watt Music Reference RM10 at John Rutan's Audio Connection, when he and I were hanging out with one of his salesmen one afternoon several years ago.

That was simply one of those few and fleeting magical moments we all experience in audiophilia. Nothing was lacking. Even the low end, which was incredibly fast (normally, one the Vandersteen's real weak points), and possessed true snap. Ahhhhhhhhhhhhh, I close my eyes and can hear it all over again - Dick Dale's surf guitar has never sounded finer to me.

Also heard the speakers with a pair of Quicksilver monos when I was last there in November, and though good, didn't come anywhere close to the aforementioned experience.
I also heard the Vandy's at AudioConnection in Verona played by John Rutan! One of the best sounds in a dealer showroom I have EVER heard. Played a Terry Evans CD that just sounded so alive.
I used one of these 25 wpc in a room bigger than yours:
It's really more important that you have some current behind those watts. For example, you could use a pair of Dyna MKIII's but you won't like the way the bottom end sounds. Sixty tube watts is sufficient if you don't play your music loud. Just use a tube amp that has some decent energy storage. Most of the ARC amps do. Roger's amps do as well i.e. RAM Labs/ Music Reference. Just remember, current controls the bottom end on dynamic speakers.
Yes the VTL IT-85 is sufficient.
I am using 2cesigs with a Music Reference rm9 mkll and I couldn't ask for better. The bass is as much as I could ask for. The Rm9 is the only component I never think about changing.
Believe it or not, the best I've heard Vandersteen 2s (and I've heard them a lot) was with a 35 watt Music Reference RM10...

This is really good to know since I've been itching to get the rm10 but was worried about it driving my Vandys 2ce sigs. Think they'd do fine in a larger room, 20x35 at moderate sound levels? [Sorry to distract from the original question.] rm9's are hard to come by.
Those 35 watts are magical, though Roger would say "nonsense" to that. But I think it would work for you. I owned the Music Reference RM9 Special Edition which was a limited run ($10,000), point-to-point wiring version of the RM9 with a different driver stage than the std RM9s, that put out 162 watts into 8ohms. It was one of the finest amps I have ever heard - the RM10 was good enough to let me sell it, something I never thought I would do. Buy one used, you'll sell it in a few hours if it doesn't work for you in your room - only you can tell. You could also get two and run them in mono for 70 watts/8ohms if you love the sound but just feel the need for more power. Roger had them on sale for $1550 during the recession, might still be able to get them at that price. I use mine with Merlin VSMs which are more sensitive and an easier load, but I run it off the 4ohm tap which drops the power to 27watts (but more current reserve)and it never, ever, seems to be running out of juice. I think Richard recommends 40 watts min with the 2s, but I would trust Trelja's observations (they are tube watts afterall.)
Buy one used, you'll sell it in a few hours if it doesn't work for you in your room - only you can tell.

That's the problem with trying to find a used RM10--they vanish before I can even see them. Happened just yesterday. Didn't even get to see the price.

I think Richard recommends 40 watts min with the 2s

He does and that's what prompted my concern. But Trelja's observations pushes me over the edge. The smallest Atma-sphere S-30 would probably do well as well? But those seem to be even rarer than the RM10's.

To the original poster: there's an upgraded RM200 for sale right now (no relation to me) at 40 watts. Too spendy for me, but might work for you.
I think the S30 would not be a good match, very different kind of amps in terms of delivering current. I think you would need M60s and maybe even Speltz autoformers to drive Vandersteens with the lower powered Atma-spheres, but expecially the S30 - not ideal, I would think.
Thanks Pubul57. Good to know since I would have bought them had they shown up at a decent price. the M60's generate too much heat, I've read. I live basically in the desert, so no go.
Back to your original question though, and already answered, if you like the sound VTLs (what's not to like)85 watts is enough watts:)
I had not noticed this reference on Roger's website before, but somewhat relevant:

"The RM-10 came into being in early 1990, when I noticed I rarely played music above a few watts on my Vandersteen 2C speakers."

Banquo363, a 20' X 35' requires something serious to pressurize the room the way some require. You did use the word, moderate, so I would say it comes down to how much of a headbanger you are.

I agree with Paul's comments regarding the RM10, and he and Rnadell on Music Reference amps in general. If you can buy an RM10 for $1550, in my opinion, that has to be one of THE flat out biggest bargains in high-end audio.

In my experience, there's far more to how a loudspeaker and amp couple than just watts. People will throw a lot of other numbers and specifications out there, but I'd say oftentimes need to give the match a try, as some surprising things can happen. I would have honestly scoffed at someone suggesting I listen to a physically diminutive 35 wpc EL84 based tube amplifier with the Vandersteen 2s before hearing what I previously described. Shows you how much I know...
Gotta stop checking this thread or else my credit card is going to get dinged. Website lists at $1950. I'm not sure I want to find out whether the sale price is still good, but...
They call it the IT-85, but I think it specs more like 60W even in UL mode and the amp works in triode mode too, i think. :) ** the amp does have pre-outs for running another amp, so that may be usefull too. I have considered buying one, so I know a little about it.
The discount price was never listed on the site, but Roger announced on his Audiocircle forum, and it was confirmed when called 2-3 months ago.
IME 60 watts in plenty for the Vandersteen 2s. They are easy to drive with most tube amplifiers. In the case of the M-60 you don't need the ZEROs, in the case of the S-30 I recommend trying it both ways and see.
I had Vandersteen 2C Sigs powered by a 45wpc CJ CAV 50 and this was plenty for them.
Well, I just bought a RM-10. So, I'll see very soon whether 35 tube watts can drive the vandies in a sizable room. Fingers crossed. Will report back.
I have the Vandersteen 2CE Signature II and I was driving it with the NAD 2100 that are set to Bridge (mono) at 300wpc. The sound is awesome and I love it. BUT, when change the NAD to my old McIntosh 2100 rated at 105wpc in stereo mode, the sound became more alive as in the low bass is a lot fatter and more natural and cleaner mids and highs. But if I or you guys can get a tube amp, it will even sound better I mean a lot better.
Full day of listening to my newly acquired RM-10. I had it light loaded on the 4ohm tap for the 7ohm rated 2ce sigs. After 4 hours like that and being rather unimpressed by the sound I was getting, I used the 8ohm tap. Far superior in my set up. Sound opened up and more dynamic. I'm not drawing any conclusions obviously but I'm not too anxious to go back to the 4ohm setting either. With my LSA passive preamp at 2-3 o'clock the amp had plenty of juice for the Vandersteens in my sizeable room. The bass is surprisingly tight and full. Any edginess and brightness that I used to have with my ss amp is pretty much gone.
Maybe it was breaking in? I would try the 4ohm tap one more time after it has broken in for a while and you use to the sound of the amp. I'm curious what you think then. A great little amp - isn't it?
I don't believe that light loading the RM10 would reap any benefit while driving the 2ce either, particularly if it sounds better from the 8 ohm tap.
The choice of tap may very well be speaker dependent however,the 8 omh tap has been the definative choice with each and every speaker speaker I have paired it with.
Tannoy Westminsters, Merlin VSM,proac 2.5, and a pair of vintage quad 57's.
Ecclectique, any idea why that would be given Roger's comments on the benefits of "light loading"?
Hi Pabul57. I am not sure about Rogers comments with regards light loading however,it is impossible to ascertain with any certainty which tap is appropriate to use as no loudspeaker represents an unchanging impedance at all frequencies.
The 8 ohm tap typically match loads between 4 and 8 ohms, the 4 ohm tap will be a better match for impedances that fall below 4 ohms.

The one thing that I am more than certain of..... The 8 ohm tap is far and away the right impedance choice for the Merlin.
If you use the 4 ohm tap on an amplifier with a speaker of higher impedance, the output transformer will be inadequately loaded, and so it will express less of its winding ratio and more of its inter-winding capacitance. This can result in the amplifier no longer having flat frequency response. In addition, the transformer can 'ring' if inadequately loaded, which is another way of saying that it will distort.

The Merlin is an 8 ohm load, with a dip to 6 ohms or so. Its a benign load and an amplifier with an output transformer, if the transformer is designed properly, will likely work best on the 8 ohm tap. This will minimize the artifact of the transformer.
Modjeski comments on his RM10:

"The amplifier is flat within 0.1dB and has low distortion of 0.3% when played below clipping on average level material. At the recommended bias current of 30mA/pair, the idling dissipation is nine watts or 75% of the tubes' rating. I estimate tube life to be 5,000 to 10,000 hours. Although higher idling currents will reduce distortion, it can also be reduced by light loading. Basically, light loading reduces the output current demand on the output tubes, allowing them to be more linear. It also reduces noise, raises damping factor, reduces distortion by 78% and allows for 80% more peak current when needed. The only loss is about 20% of the power rating or 1dB." Light loading means connecting the speaker on the tap that's one half its nominal impedance rating (i.e. the 4-ohm tap for 8-ohm speakers). For 4-ohm speakers, the he recommends running two RM-10s bridged to 70-watt monoblocks.
In my limited experience w/my new RM 10, the light loading seems to have the best sound w/my speakers which are around 8 ohm min. impedance & 92dB. It's the best audio purchase I've made to date.
I prefer the light loading too, but I do wonder why Ecclectique has had a consistent preference with using the 8 ohm tap. That of course can be explained depending on the speaker, but he did say he tried it with Merlin, I'm using the VSMs.
This proabably should be a new thread since it is ain interesting topics, and was interested in what Ralph had to say. Not that OP has gotten his answer, but not sure others would find this topic buried in a Vandersteen discussion.
I listen to records 95% of the time and didn't even think to use my CD player with the rm10--until today. To answer the leading question of this thread: the 35 watts of this amp is more than sufficient for Vandersteens in a sizeable room. I have my passive preamp at 10 o'clock and I can't imagine wanting it any louder--or better. A Love Supreme never sounded better on my system. Earlier I was listening to the the Bob Ludwig remaster of Leonard Cohen songs and was moved beyond reason. These CD's have always sounded good but good grief I was in for a pleasant surprise. I had the privilege of hearing Cohen live a few years back in LA, and I don't hesitate to say that the emotional connection I had listening today was nearly equivalent to that live performance.

I am surprised by this as, to be honest, I've been somewhat disappointed with my vinyl playback with this amp. There are a lot of changes going on in my vinyl rig so I'm not drawing any conclusions.

At any rate, if my cheapie CD player can produce this sound then maybe I won't continue dumping untold dollars into vinyl. Or: I'll just blame the phono stage and continue on.
Not bad for an amp the size of a book - is it? :)
A small book - not Websters Unabridged.
I have the IT-85 with upgraded caps in my bedroom driving a pair of Dynaudio Special 25's... You should be fine (at all volumes).
Pubul57, the act of increasing the bias on the tubes has the effect of reducing their output impedance. This will change the relationship they have to the output transformer.

In addition, you have to also consider how the amplifier was designed. For example, many power tubes want to see about 3000 ohms plate to plate. But what if you had the transformer designed to be 3500 ohms plate to plate? You might loose a little power, but now you can experiment with different taps to affect the sound in different ways. This is because the transformer really does what it is called- it transforms impedance. The load that is on the output taps will affect the load that is on the tubes. Especially in the last 30 years, its been a good idea to build in a little reserve to deal with the many 4 ohm speakers out there.

So if in the above case you are loading the 4 ohm tap with an 8 ohm speaker, the result is that the tubes might see a load impedance that is much higher, perhaps 6000 ohms. Now in some cases the amplifier will not be able to make as much power, as the voltage that needs to be made across such a load to get the power is no longer available. But it may not matter if the power thus obtained is sufficient.
One of the best times we had with the Vandersteens
and an RM 10 was when Traveling sales fellow showed up with pair of huge golden gridle Prototype OTL 10 inch tall 30 deep mono blocks.
After listening an hour or so he said so wad do ya think
I said hold on and reached for the bible size RM 10
wired it up, we looked at each other and I said you in trouble....
Its the output transformer
Old Testament only.
Ok I'm not sure if im jumping in the right way as I'm new to audiogon lol i picked up a nice pair of vandersteen model 2ci the guy i bought them from had a old Kenwood integrated 60w per ch driving them i was impressed with them for $550.00 i thought they were a steal got them home connected them to my Cambridge Audio 840a integrated that I thought was far superior to his old Kenwood integrated i was wrong ramping up the vol to my favorite tracks of  Stevie ray and double trouble the Cambridge was quickly clipping so when reading about the sound achieved with the Vandersteens through tubes i thought for sure i was going to need at least a 100w tube amp but then i here about current?  & output transformers I'm just afraid I'll buy something and be disappointed anyone have a take on primaluna prologue or quicksilver mid monos ??
Hi moronpainter and welcome to AG. 

I cannot suggest this strongly enough- use punctuation. 

So so hard to read posts without punctuation. 
Well thank you so any thoughts on amps for my vandies?  
You do not need more than 60 wpc
Shuguang classic s8km integrated?