the VSi60 now comes standard with KT-120s ARC does not claim a power increase. I never heard the VSi60 with the 6550s but I have listened to both tubes in other amps and the KT-120 gives you a little more headroom and microdynmics as well as better bass.
You might find using KT-120's instead of 6550's, if it's possible with that integrated, may give you a bit more headroom and a bit more slam in the bass.
You make a strong case. A good tube power amplifier does seem to present/capture more emotion of the music and possesses that 'breath of life' factor that I seem to find less often with SS amplifiers(there are exceptions).I know exactly what you mean.
I own a pair or 804s as well as a pair of Wilson Sophias. I just had the vsi60 for an in home demo for about a week. Compared to 200+wpc solid state amps from the likes of Bryston4b-st, Rotel rb-1582 and Krell kav-250 the only thing you are missing is a small amount (3-5db) of headroom however most of the music that you are listening to does not have huge dynamic swings. What you gain is an expansive soundstage holographic highs and an extremely magical midrange. The VSi 60 also does something intangible it just seems to pull you into the music more. My advice is to get the vsi60 and a decent sub and love the music your system is producing for years to come.
You need a good sub. The 804S will miss most of the low bass Pink Floyd material. After the sub start looking at amps. The vsi-60 will probably be fine for that speaker.
You can still satisfy your tube fever, it will just take more tube power than you originally thought.
I thought would need more power but I think I have tube fever.
Thanks for the help
It is unlikely you will have good results driving 804's with a VSi60. You might want to consider an amp from Levinson or Pass in the 200 watt range.
My setup is in a 1200 sq ft loft apartment with 9 foot ceilings.
You make some good points,I certainly agree about transformer and PS quality.
It`s hard to answer posts like these when important information is omitted i.e.room size,listening level range etc.
I agree with Brf. If you are a fan of Pink Floyd ,Radiohead and harder rock music there is a good bet you like to turn the wick up and for that more power would be recommended.
I am not suggesting that you go solid state, but when the speaker manufacture's own specs state a minimum power requirement of 50w - 200w coupled with an impedance dip below 3ohms, I get concerned about an integrated tube amps ability to drive the speakers. Typically, one thing that gets sacrificed with integrated tube amps is the quality and size of the output transformers.
We all agree that a mismatched amplifier to speaker combination will not yield long term satisfaction. If you do not have a chance to audition the amp personally, then I would error on more tube power based on your listening criteria and the speakers specification.
What size is your room and what db levels are you listening at?these factors really matter.
If the ARC amp has a very good power supply and transformers it could be just what you want.
I would`nt buy a SS amp just for a stated higher watt output, sound quality is the objective.
Based on your listening and music preferences I would look for an amp with more power. Tube amps when driven to their maximum output have soft clipping which gives the listener the impression that they have more power than their solid state brethren, but in reality, you are listening to a distorted sound.
The B&W 804S specification places the Audio Researches vsi-60 at the minimum standard for amplification, but based on your listening requirements, I feel that you need more power to give you the clean undistorted sound that will satisfy you in the long run.
Just to give you an idea, here is an iphone video of the VSI60 driving my new power hungry Studio2's in a HUGE room. This amp is not even half broken in yet and the speakers had only 5 hours on them when this was taken. The amp really only runs out of gas at ear bleeding levels.....or on very bass heavy stuff or orchestral works....
In a reasonable size room, you will have NO problems.
Just try to make sure the VSI60 has the newer KT120 tubes
they are now shipping them with because it gave them a bump from 45wpc to 55wpc. These are conservatively rated, and real practical power rating would be closer to 100wpc in real world application. My room is 27x17x10 and I had Vandersteen 2CE Signatures which had sensitivity of 86db/1w. Yours are 89db/1w, which may not sound like much, but yours need HALF the wattage versus mine to achieve the same level.
The VSI60 is a magical amp. Mine has 200 hours. I am going to have to part with it because I just upgraded to Revel Studio2's and they eat juice like crazy so I've gone to 350wpc Pass but am staying with an ARC tube pre. This amp made my Vandersteens come alive with music like no amp before and all the ones before were far more expensive.