Sim W-5 vs Pass X250 / X350 with Dyn C-4

Has anyone used a Pass Labs X250 or X350 with the Confidence series of Dynaudio speakers?

I currently have a Simaudio W-5 driving my C4's. On occasion with 2-channel music, where I run the speakers full range, it seems to possibly run just a tad short of punch and I was considering a more powerful amplifier and was looking at the Pass Lab X250 or X350. For movies I have never noticed any shortness of punch, but for movies I run the C-4's crossed over at 40 Hz and the lower end routed to the sub.

I would love to move to the Simaudio W-8 or a pair of W-6, but the cost, even for a used unit, is beyond what I want to pay.

The thing I like is the Simaudio W-5 mates well with my Simaudio Titan that is driving the center speaker (Confidence Center) for movies and I might not get that match with a Pass Labs unit. It also drives the surrounds and rears.

Any thoughts or experience on the mattter would be beneficial to my decision.

Current System:
Preamp/processor - Anthem Statement D2v
CD Player - Arcam CD192
DVD Player - Denon 5900
Preamp/Amp Interconnects - Balanced - Canare
Speaker Wire - Kimber 8TC for fronts
Based upon my recent 3 day stint with pairing my C4's with Sim W6's, I found the presentation of the W6's to be lean & accentuating the higher frequencies at the expense of midrange frequencies, warmth & decay/micro-dynamics. The Sim sound in my experience was not for me. I've decided to stick with my Plinius SA-102. If I had space in my rack to accommodate the massive Plinius SA-250 Mk IV, that's the direction I would head. I have also heard from a previous owner of C4's that the Pass X250.5 was a synergistic match... but then again, I hear the same things about Dynaudio & Sim Audio. I guess it comes down to personal preference.
My friend has the X350.5 with his C-4. He was using the ML432 prior. Then he heard my X350.5, not even fully broken in at the time, and bought one within a week.

I've only heard Sim Audio at a dealer here in San Francisco. Different setup, different room. But I agree with Pdreher that they sounded dry, edgy, and "solid state".

My friend has been playing with his pair of C4s for at least two years. His biggest complaint is that these are finicky regarding placement, most noticeable with the bass region. So I am not sure if it is due to the speakers or his room. But I do like the sound of his C4s with the X350.5/ARC Ref 3/PH-7/Clearaudio anniversary/Audio Aero CDP.

I had heard the X350 and X350.5 side-by-side at another friend's place before I purchased mine. There is a big difference between the X350 and X350.5. The X.5 series has more of the midrange magic similar to the old Aleph series. The non X.5 series sounded cold and "solid-state" like.

FrankC - tell your friend with C4's to add some GIK (or comparable) room treatments to tame the bass and reflections. I was about to give up on my C4's, then added 8 GIK 244 panels to my room and it turned the C4's into keepers. Adding room treatments was the best / most cost effective thing I've done since getting into this addictive hobby. Adding a tubed preamp with NOS tubes also paid nice dividends, but not to the same extent as adding the room treatments.
I am going to give the X-350 a try. I know that from reviews, etc. that I may be missing the fluidity of the X-350.5 midrange, but for now it is out of the range I want to spend. Maybe if the year goes well and there is a nice bonus at the end, then maybe I can move up....

I am going to wait to sell the W-5 so I can do some comparisons.

Thanks for the input.

I've never understood the Sim/Dyn relationship---its just a marketing relationship to these ears.

Pass 250.5 was beautiful with my C1s. BAT ss would also work well.

Dyns don't like bipolar amps in my view, although i would like to try Krell on them and think that is the only one that could work.
IMO I would go with the X250.5 before I would buy an older 350..I have C4s and the 250.5 mates wonderfully..Im running a MC 402 at the moment but Pass is back in the headlights for me
Keithr - I have to agree with you on the Sim / Dyn relationship. My system is very warm (Jade Hybrid IC's, NOS tubed preamp, tubes in both of my sources), but it was not enough warmth to tame the Sim's brightness. The Sim did some things well... just not enough for me to keep them.

Agree with Missioncoonery on getting the more current Pass 250.5, rather than the older Pass 350. Would also love to hear the Plinius SA-250 MkIV with C4's, based upon my positive experience with the SA-250's little brother, the SA-102.

I've also heard the Dyn C2's with a Krell amp... I think it was from the FPB series. Sounded very dynamic & transparent with a huge sound stage. Really kinda surprised by how good it sounded, based upon all of the Krell bashing I've read on this board.

In my experience, both Plinius and Krell where better matches than Sim with the Dyn Confidence series... YMMV.
Before you trade out your amp you might want to try differant interconnects. In the past I felt the Canare cable to be on the lean side and restricked the bottom end.
It did great things with the mids to treble but not the bass.
i think a tube preamp/Krell amp would be match in heaven for C4s and i wanted to do exactly that (Cary 05/Krell 400cx) with my C1s.

in the end i didn't want to spend the dough, so i use a BAT integrated, which is remarkably synergistic.
Comparison – Simaudio W-5 versus Pass Labs X350 with Dynaudio C-4:

I switched out my W-5 with a Pass Labs X350 last night - I actually switched back and forth for a while. After a few hours of listening to music (CD and SACD stereo) I can make the following comparisons:

My listening was done at both moderate and higher levels. I do not know how many dB’s I was cranking at the high levels, but it was not insignificant.

The X350 throws a larger soundstage, but the imaging is not as precise as the W-5.

The X350 wins the war on the lower end bass and control. The bottom end was significantly fuller and more defined with the X350.

The W-5 wins the contest for the midrange. The midrange on the W-5 is much warmer and “sweeter”. The midrange on the X350 is very precise and almost analytical – somewhat “dry”.

The top end highs were the closest of all. The X350 might be just slightly “rolled off” as compared to the W-5, but it also seemed more precise.

All-in-all I would call the X-350 provided a fuller and dynamic, but somewhat dryer, presentation over the entire range. The W-5 has the best midrange and vocal presentation.

One good example I can give is in the Diana Krall song “Peel Me a Grape”. The presentation of the vocals with the X350 was more forward. The vocals on the W-5 were more laid back into the soundstage and smoother. However, the presentation of the string bass with the W-5 seemed to be a little “plunk” in the background. With the X350 when the string bass hits at the start of the song I could hear it as well as feel it.

Having been to one of her concerts in a pretty intimate setting I can tell you that the bass does have the impact of the X350 and she presents the vocals more laid back than in your face.

As indicated above, the Pass X350.5 might give me the best of both worlds, and maybe a higher powered Simaudio (W-7 or W-8) might give me the bass impact of the X350 with the sweetness of the Simaudio midrange.

Which will I keep……………probably the X350, but I have to try them out with movies first over the weekend.
i think the .5 series is a monumental improvement over the other. you with get the detail and bass impact that you are seeking.

the older X series is pretty soft, i agree
is the .5 series a bit warmer or easier on the ears? It seems there have been a lot of comments about the older series being a bit dry. I have the W-3 and I do not find this the case at all, but I have a warm pre and forgiving speakers. I also like the sense of depth, soundstage and air it presents in my system compared to other more expensive amps that I have. Anyone heard the Evolution Series?