Tube vs Solid State - Comparable Output?

Don't use a tube amp on a speaker of low impedance, PERIOD. Neither the amp, nor the speaker will sound the way it should. I know some tube amps that appear to drive 4 ohm speakers well...until you listen to them on a speaker with an 8 ohm or higher impedance. Your friend sounds like an idiot.

I have heard that a low impedance speaker, like an electrostatic, it will eat tubes like there's no tomorrow. On the topic of equivalent power. I've had 100w tube, 160w tube, and a 185 w solid state amp in my system. I can attest that the solid state is MUCH more powerful in terms of controlling the speaker. They are not even close. I do not drive my speakers to high levels, so I cannot comment on clipping points. I also note that when people talk about a tube amp having good bass, it is in terms of a tube amp. I had two high quality tube amps, and neither had even a shadow of a solid state amps bass control. The amps were AR vt100m2, Sonic Frontiers SFM-160's. For solid state I have , a McCormack DNA1/AGold. The SFM-160's actually had internal jumpers to that you could set for 8,4,2 ohm loads. The vt100 had 4 and 8 ohm terminals. I have also had my old 125w Denon receiver hooked up to the speakers, and although the sound quality was lower, the bass was still more powerful than either of the tube amps. I've driven Vandersteen 2's and 3s (8 ohm), and virgos (4 ohm) with these setups. The vt100 seemed to be a little wimpy with the vandersteen 3.

I understand the theoretical differences which suggest solid state should be better than tubes in the bass, and ditto for low impedence speakers. But, in one of my systems, the best amp for bass, and for the Martin Logans and Thiels they drive is a tube amp. This is despite trotting many solid state amps through the joint (Krell, Classe, Aragon, Ocean, Lewitt, Plinius etc). I suspect the bass is better with tubes because the floor is suspended across spans of about ten feet - meaning it sucks bass somewhat. Using high-damping factor solid state amps the bass sounds almost swallowed. The tube amps (admittedly very good ones) have more realistic bass, with tightness, extension and air. I do not make this point to negate what has been said, only to point out that some situations prove to be the exception to the rule.

Thanks for the input, guys. I've recently purchased a pair of Martin Logan CLS II's (non Z version). Not set up yet due to a recent move. My McCormack DNA 1 Deluxe has done a good job of driving my Apogee hybrids and I'll try it out with the CLS's. Since the CLS's don't go to high Db levels or very low in the bass, my thought was that maybe something like a VT100 might do a better job in the mids and provide more air -- the liquidity of a good tube amp might be a good match for the transparency of these speakers. I guess the only way to find out is to try both. Audio Research is coming out with a MK III version of the VT 100, so there will probably be good deals available soon on MKII's. Yeah, replacing the tubes is a hassle and an expense, but if the sound is right I can live with that (I think). But I still question this amp's ability to deliver the required current to these very difficult to drive speakers (impedance can dip to .5 ohms). Thanks again for all of the information. Jim