Plinius SA250 Mk.4 vs. Pass Labs X350


Anybody compare these two ss amps? I'm considering upgrading my Plinius SA100 Mk.III amp. My associated equipment is Audio Research Ref. 1preamp, Meridian 508.24 CDP, Dynaudio Contour 3.3. Using NBS Monitor I XLR interconnects, NBS Monitor III speaker cable. Your thoughts/feedback are greatly appreciated.
rosstaman
Unfortunately, I live in the Sierra Nevada Mountains near Yosemite Park. The closest high end audio stores are three hours away and they don't carry either Plinius or Pass Labs. To go to the greater Los Angeles area to hear these units would be over 8 hours away and LA is always a nightmare to travel in. So I'm hoping so of the audiophiles here can be helpful in my making a decision.
Have been in this hobby since 1957,and have owned countless gear.Had tubes when that was all there was.Have owned many Nelson Pass products from Threshold,and I have heard the X350.If you can afford the X350 -- BUY IT --.But b forwarned the Pass X350 is intolerant of weakness in the component chain and will expose those weakness's.I own Threshold Class A amps. They are rock solid in every respect.I have tried other preamps with the Threshold amps but always come back to the Threshold PreAmps,as the match to Threshold to Threshold is clearly superior.I would dare say the same could hold true for the current Pass Labs product. The X350 I listen to was using a Pass Labs preamp. If and when the Threshold gear gives up the ghost will be going to Pass Labs.Lets face it Nelson Pass had the ground breaking white paper on Cascode design in the late 70s and was awarded a patent for that design. He has been further refining that orginal design.Make no mistake Nelson Pass designs and products are timeless.I have wasted far too much time and money trying to find better product.
What about the SA250MkIII with siltech silver wire upgrade vs. an SA250MkIV? The MkIII can be had at bargain prices these days. Is the sonic difference between the two worth the difference? I know this is slightly off topic but I think those reading this thread would be interested in this issue.
You should check it out, but I believe the only difference between the MkIII and the Mk IV is the upgrade to Siltech silver wire.
Rayall: My understanding is that the MKiv has 4 separate toroidal transformers...and that the MKiii has one large one. In terms of sonics, many say that they are very similar...but some state that the MKiv was a significant improvement. The question is.....how much better is the IV if at all...and how much is that worth. This hobby is fun...but also can drive a person up the wall!!!!