From Pass X250,5 to 350,5 : what to expect?

Overbang, what speakers are you using?

If the circuit design is the same, which I think they are, I would think lower power always sounds better if it is sufficient power to drive your speakers in your room to the listening levels you want. There is a thread called "Power - Good or Bad" that has lots of comments on this type of question in a more general sense.

You need sufficient power for dynamics, but your speakers determine whether or not a certain number of watts is a lot or a little. More power tends to corrupt the signal with more wire, parts, and complexity - so if you have sensitive speakers with benign loads you can take advantage of the inherent quality of lower-powered amplification. But yes, you do need enough power - no question, but that is a relationship between amp and speaker - with my speakers, 30 watts is a lot of power, with some speakers 100 watts is too little.

250 watts and the current drive into low impedances would seem to be plenty of power to deafen you with the Revel Salons, unless you have a really big room. I would think 110db would be plenty loud, the 350 would only increase the output to 111-112db, I would think you would be running out of the room before you could tell the difference. Again this is assuming the 250 and 350 have the same basic circuitry, dam[pening specs, and drive into dipping impedances.

Fatcataudio, what speakers did you use for your evaluation?

Well, I can't argue with what you experience, it just seems hard to believe that going from 250 watts to 350 watts can make any noticeable difference with fairly efficient speakers with smooth impedances (which I think most Proacs are). Now it may be that the Pass 250 and 350 have fundamentally different circuit and/or parts, but I did not think that was the case, just more watts, and in this case just enough additonal power to play 1db louder.

Well the NFB would be a signficant difference for sound quality and that might explain the difference some have heard, although I suspect the 30 versus 50 in Class A would not be to relevant with the Revels.

Tboooe, I think all your assumptions are right and your conclusion regarding the need for power is right - we generally need a lot less than we think. I would only argue that given the same basic design approach, the lower power version of that design will sound better at a given volume level if the amp has enough power to reach that volume level with a given speaker. In the case of the 250.5 versus 350.5 comparison, the more powerful amp may sound better in this case if it is a no negative feedback design and the lower power amp isn't.

The design differences between and the X.5 and XA.5 are quite "drastic". And pure Class A watts are not the same as A/B watts - in part because there is more to power and sound levels than just watts. By the way, Ayre is also first-class SS amplification - can't wrong with them either.

The X series also doubles power, always has. But the XA is a better sounding design if sufficient power. The XA100.5 is wat more than enough power with the Revels for 99.99% of the time is most rooms.