Class A 30 Watt Amps: Are they enough to drive my book shelfs?


Currently looking at buying a Pass Labs XA 30.5 to drive my Kef 201/2 speakers which are rated at 86 DB sensitivity.  Is this a bad move?
puffbojie
@atdavid, the Pass XA30.5, as well as the XA25 which I use, and I believe most or all other Pass XA amps, operate in class A up to and somewhat beyond their specified power ratings. (I say "somewhat beyond" in part because those ratings are specified very conservatively in terms of distortion percentages). But at higher power levels these amps transition to class AB, resulting in much higher power capabilities than are specified, as illustrated by the reference Twoleftears provided above.

To provide an additional example, my XA25 is specified as having capabilities of 25 watts into 8 ohms and 50 watts into 4 ohms. Yet Stereophile measured 80 and 130 watts per channel into those impedances, respectively, at 1% THD + noise.

Also, the paper by Nelson Pass on "Leaving Class A" that I referenced earlier in this thread may be of interest.

Best regards,
-- Al
Unfortunately when I was looking at them, most articles described them as "pure" Class-A, not high bias AB like they really are. Thank you for clarifying.

Last question : This is for a 10x14 bedroom in AZ.  Will the amp run so hot that it generally becomes impractical for this space? 
Will the amp run so hot that it generally becomes impractical for this space?
Since the amp will be operating in class A the great majority of the time the amount of heat it puts into the room will correspond to its 200 watt specified power consumption (assuming that spec is accurate) minus the amount of power delivered to the speakers at any given time. And since most of the power delivered to the speakers will be converted into heat by the speakers anyway, as a good approximation you can expect that the amount of heat put into the room will be similar to the heat put into the room by any device which converts the great majority of its power consumption into heat and consumes 200 watts. Such as two table lamps each using a 100 watt low efficiency incandescent light bulb (the kind that have now been mostly phased out).

Regards,
-- Al
My XA30.5 is in separate 10'x12'x8' room from my main system. I didn't have room for it in my media cabinet, and my wife didn't want it on the floor.I can keep my hands on the fins of the 30.5 comfortably for as long as I like.The fins are warm, but not hot to the point you have to worry about children touching it (like tubes).
It's one of the cooler running class A amps out there.I get more noticeable heat generation when my Dynaco ST-70 amp is running for a few hours in that same room.
That said, I live in the NY snow belt and not Arizona. Al's reasoning above is excellent. If you can handle a couple 100 watt bulbs firing away in that room without needing to crank the AC, you should be good.

If you want a similar XA30.5 sound without the class A design, the Jeff Rowland Model 2 is pretty close in sound. More delicate and finer grained. Zero heat due to it's AB design. Kind of hard to find these days though.