Tube Amps Watts vs SS amp

If you are starting with the premise that you need 400 wpc, and you have a somewhat tight budget restriction, most tube amps are not good candidates.  I think that even ultra expensive high powered tube amps don't sound very good and would stick with solid state for delivering that kind of power.

But, are you certain you really need that kind of power?  There are meters that can tell you how many watts are being delivered to your speakers.  If you use one of these meters while playing at typical volume levels and at the highest volume levels you play your system at, you will have a better idea of your power requirements.  If it turns out you do need more than 50 watts, it might best to just stick with solid state.

I too have heard the claim that tube watts are subjectively more powerful than solid state watts, and I have sort of felt that way myself.  I actually think that good tube amps, coupled with appropriate speakers, sound much more lively and engaging than solid state amps playing at the same volume; you have to crank a solid state rig up to a higher volume to get the same sense of liveliness, hence, the impression that tube amps sound more powerful than their rating. 

The actual numbers would suggest otherwise.  The published tube amp output is typically where the tube is actually distorting quite a bit, and a more comparable wattage rating to where solid state is rated would actually be MUCH lower.  Arguably, a tube watt is less than a solid state watt, but the subjective impression is quite the opposite.

The AR 9 is somewhat of a beast to drive (87 db/w @ 4 ohm nominal impedance).  While it is possible to use a small tube amp successfully, it would mean accepting modest sound levels, a smaller room, etc.  I think solid state is more likely to be the best choice, but, you never know unless you audition some tube gear in your system.

I find it interesting that so many audiophiles, particularly those who favor high-powered amps, measure quality by how loud an amp will play.  For me, the measure is just the opposite--how soft can an amp play and still deliver satisfying sound.