PassX-250 vs PassX-350

I have the X-150. I'm looking to upgrade. I love the 150 but I want more power. Is it worth it to spend the extra loot on the 350,or is the 250 a close sonic match? Also how will those amps match up with a BAT tube preamp? I appreciate any help or suggestions.
(disclaimer: I sell pass gear)

I would definitely go with the X350. If power is any question you want to get that amp. It jumps from the 'will power most speakers' X250 to the 'Will power ANYTHING' X350.

I have matched the 350 up with a Bat preamp (vk-5i) and found it was quite a nice combination. Since the Pass gear is so transparent it lets the character of the feeding source come out more.

(disclaimer: I sell Pass Labs gear)
What is your speaker's efficiency? The 350 will run in class A louder than the 250, and that will affect your perception.
BTW- I am using Martin Logan Ascents.

I use an X-250 with Martin Logan Aerius i's, along with a Pass X-3 for rears/center. They replaced Bryston 4B-ST & 5B-ST's. The Pass amps are sonically miles ahead of the Brystons with these speakers, even though the similar specs do not suggest that they would be. I considered the X-5 or an X-150/X-3 combo before buying the X-250 & X-3, and talked to Pass Labs about the speakers I was using. They knew the Aerius well, and definitely recommended going up to at least the 250 for the front mains.

With ML's, you want current - lots of it. I don't think you could ever over-amp these things. But I find the 250 can handle driving these speakers that drop to 1.2ohms at 20khz quite well.

Would the 350 do it even better? - Probably - just as RangerAudio suggests. I just could not justify running $2300 speakers with a $9000 amp, nor could I afford it. Besides, I bought my pristine 250 used (right here on the 'goN!) for a great price. I have no regrets or desire to upgrade above it now.

FINAL NOTE : Just yesterday I replaced my Aerius with Talon Raven 2002 speakers with Khorus-X/2 CMRC crossover upgrades. So far, the synergy of this Pass amps/Shunyata Lyra cables/Talon speakers combo is proving to be quite magical and dynamically powerful. These are not, of course, electrostatic speakers, so they are an easier load on the amp.

Hope that helps,
Bob Houser
Thanks Bhouser,and everyone else for the advice. The X-350 is 9K,but the used price recently is around 4K(actual ads)If I sold my 150 it might only cost me a couple grand more for the 350. Regardless I'm sold on Pass,and my decision is narrowed down to the 250 or the 350. I probably can't go wrong with either.
I spoke to Peter at Pass and he helped me with some of the differences between the amps. The x150 and x250 have similar circuit designs with only some localized feedback around the output stage. The X350 and larger amps have the zero negative feedback characteristic which adds to their lushness and overall neutrality.
Nutella, that's new to me. I never heard the X150 and 250 use feedback while the larger ones don't. I do know, for a fact, all X amps employ a small amount of feedback in their supersymmetry circuits to help equalize distortion matching. As far as I have read, that's all.

Still, when I switched an X150 for X600 monos on 4 0hm speakers, I noticed more than the expected bass improvement. the midband was both warmer and it had more body. It is my guess the class A operation of the X600 accounted for the different performance. That is why I am voting for the X350 in Krelldog's case.

Bhouser, I am running $1500 speakers on $16,000 amps. If the speaker does everything you want, and it asks for the power, you feed it.
I thought that was what I said. Rather, what Peter said.
For $4000 used I'd also opt for the X350
Nutella, I agree with Muralman1 - news to me. In fact, my X-250 manual indicates the opposite, that both 250 & 350 use similar levels of (meaning Zero) feedback.

However, I certainly don't deny that the 350 is 'better' then a 250 in all aspects except the obvious one - the damn thing is TOO HEAVY !!! hehe.

So, if you can get one for $4000 (I paid $2800 for my 1-year-old 250), then I would say go for it. With the resale of your X-150, you are not expending too much jack. With the speakers you have, I guarantee you will not regret such a move.

Muralman1- I have taken care of my mental block of using 2k speaks with a 6k amp - I bought 7k speakers!! (there's no audio problem I know of that can't be fixed by spending more money ;^}.
Good for you. Peter (right up the hill from me) might not like me saying this, but it's their fault - Pass Amps are so dependable, buying used is a safe bet.
Bhouser, I was being mean. Actually, I agree with your premise. That is to say, lead speakers should not be matched with golden amps. The catch is, gold can be paid for, or just found, if your lucky and/or knowledgable.

My X600 amps are pushing <1ohm, so there really is a reason for their use. The speakers were not $1500 new.
Muralman1 - NO offense taken.

"gold can be paid for, or just found, if your lucky and/or knowledgable" is definitely the main point here.

I was quoting MSRP when making this price relationship between speakers & amp, and in the case of my Aerius, I DID pay full MSRP for them a few years ago, at which point they were the best pieces of equipment IMS.

With all of my recent upgrades, I have come to the conclusion that the Aerius are now the 'weak link' IMS. I decided to stop buying stuff trying to improve the inherent characteristics that the speakers will always have and just change the speakers.

...Cut the head off the bear and he can't bite you anymore, as they say...

Don't get me wrong: I love the Martins and had serious reservations leaving the ML camp. The other speaker upgrade options I seriously considered were the ML Ascents like Krelldog has or the Odysseys.

BTW - I didn't pay anywhere near 7k for the Ravens, either - I am a true GoNNer now - I eat, live and breathe USED audio deals. The Talon dealer in Dallas (AVMaverick) sold me his near-perfect demo pair with the new CMRC crossovers, and could not have been better or easier to deal with.
Bhouser, Muralman1, I may have lost some of the details in paraphrasing what I was told so I thought I'd post the response verbatim. Sorry for any mix-up.
"In circuit design the X150 and X250 are very
similar. They both use some localized feedback around the output stage which bumps up their damping factor dramatically compared to the larger amps (X350, X600 and X1000). This higher damping factor contributes to exceptional bottom end, although the zero negative feedback characteristic of the larger amps adds to their lushness and overall neutrality. There are tradeoffs, always. However, all the X series amps are extremely dynamic, with very listenable top ends that are not forward or bright, and are very quick and responsive to musical transients."
Great info Nutella- Thanks for the clear definition.

..."all the X series amps are extremely dynamic, with very listenable top ends that are not forward or bright, and are very quick and responsive to musical transients."

I could NOT agree with this statement more, especially when I mated my X-250 with the Talons yesterday - the speed, dynamics and transients really stand out now.
Sonic signature similar but you gain X% in dynamics, bass slam, details. The BAT preamps drive any amp without a hitch. I used to own the VK-30SE with my X-250.

Happy Listening.
I went to their site and checked out the feedback issue. Nutella is right. Funny, I never saw that before, and I owned an X150. The X150 is a great amp with lots of spunk and clarity. There was nothing offensive about it's top end. It smoked a Krell KSA. I got nothing but rave reviews with it mated to an 86db 4 ohm speaker.
Muralman1- I am amazed at my x-150 too. The only upgrade I would make currently is another Pass(250-350) I wish i could afford the 600's. Thanks again for all the input.
Krelldog wrote:
"The only upgrade I would make currently is another Pass..."

Does this mean that you need to change your moniker to PASSDOG ??? B^D