Pass vs Simaudio


I am looking to upgrade my amp. My current system is Accustic Arts front end, TACT preamp, Simaudio W-5 amp and Von Schweikert vr5 speakers. I am thinking about the Simaudio Evolution series W-7 or the Pass x-250.5. Any thoughts on these 2 as an upgrade ?? Any thoughts on other amps in this price class. Thanks.
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I don't know much about the DNA-500, other than its good reputation. I wouldn't, however, include an Ayre in the mix. While, IMHO, good sounding amps, they seem to have difficulty with complex speaker loads and can sound clean and extended, but somewhat constrained. I am told that they use smaller power supplies, which limits their applications. With easy-to-drive speakers, they sound great though. I think it will be very difficult to surpass the huge power supplies used in Moon and Pass amps. Although an older design, check out the Rotel RH-B10 "Michi Series", if you can find one. No relation quality-wise to what they build today. They're extremely rare, sell fast, and sound amazing, though not quite up to the league of the Moon/Pass. However, I would put the B10 ahead of the Ayre. Again, it's all relative to what kind of sound you want.
I have a DNA-500 (currently retired) that I used briefly with my VSA VR-7's (and before that with Legacy WHispers). Great solid state amp, lots of power and musicality. It easily drove the 7's with no problem. Replaced with a VAC 300.1 due to great synergy w/VSA and desire to try the best tubed amp I could find for my application. I am not selling the DNA-500 - its is that good at its price-point.
Thanks guys. I have looked on multiple boards and can't find one person who didn't have really good things to say about the dna-500 and every comparison put it above the Pass and Simaudio. I think I will go with that. The other alternative would be to biamp with a tube amp for the top.
If your choice was DNA-500 i know you will be very happy and satisfied , had mine about 2+years with no looking back or a thought of a upgrade, that's always creeping in my mind!