Specs to look for when matching tube pre to SS amp


I would like to not make a costly mistake and learn how one determines (at least from a specifications standpoint) on how to match equipment. I have a deHavilland UltraVerve tube preamp and am looking for a new/used SS amp. The Dehavilland specs are:

Input signal: 2v RMS maximum
freq respon : 10Hz to 80kHz
noise : <80db
Max output : 8v RMS
Gain : up to 10db

The pre only uses single ended inputs and I want to match to a SS amp. My monitors are Focus Audio FS688 (85db) so I am looking at amps in the 200+ wpc range. Someone told me that I should go with an amp that has no more than @ 1.5 input sensitivity. Some of the amps that I'm looking at, GamuT and the Classe CA 2200 are in that range. I would like to consider an amp like the Blue Circle BC26MK2 as I have read it sounds somewhat like a tube amp and matches well with the Focus speakers, but it's input sensitivity rating is 4.48 to 200W. Would this create a mismatch? I believe the Pass Labs .2 series is also well over 1.5 . I do not often listen at loud volume levels. Is there more than amp input sensitivity to consider when matching to a tube preamp? I can not demo a lot of equipment, but would appreciate your suggestions. Thank you!
classical1

Showing 2 responses by serus

Why do you think you need 200+ watts for small monitors?!
Even at the rated 85dB, this power level would reproduce dynamic peaks over 100 dB SPL in a normal listening position 10 feet away from the speakers.
I know some people claim you need 120 dB capability if you want to reproduce the sound in the middle of a brass band.
Better find good ear plugs if you do... :-)
The matching between amp and speaker is more important than the power ratings, as you noticed. It's just possible that the bigger Proceed was a more refined implementation overall. In a small room, I'd look for a range of amps at whatever price level you consider. You might find that some 50W amp gives you the "right combination".
Here is a real story in that regard, where a 40W amp drove 83dB panels to deeper bass than a 150W amp. The latter was deemed by the owner as barely sufficient for the task...
The main reason I asked about the 200W amp is that it seemed odd to play tiny speakers at such high power levels, but I understand your point now.
The motivation to go down in power is simple: watts are not cheap, like many speaker designers would like you to think... To get more power, the amp designer has to make tougher compromises. Sonic ones, like the obvious need for parallel output devices in sand amps and parallel or large tubes in glassware, none of which can maintain the coherency of a single small amplifying device. Just the physics of the circuit tells you it's impossible to compensate for all mismatched characteristics between many different devices.
At the lower price brackets, perhaps the economy dictates the circuit even... IMO the best sonic bang-for-the-buck comes from the moderate power amp that matches your speakers and not from the high power one - even if it matches too.
This concept makes life a bit more complex, but when you're done with your system component selection you will most likely have the best sound for the budget when going with the "optimal" moderate power amp.