The $20K Soulution Audio 330 Integrated Amp is a Bargain ?

I've heard plenty of good things about the 509X. Only you can say whether it would suit your needs and the needs of the rest of your system and budget

I would think the Analog Domain plays more in the realms of a C/M900u combination. The following review offers a good perspective

https://www.hifi-advice.com/blog/review/analog-reviews/amplifier-reviews/analog-domain-m75d-and-m75p/

I've not heard the 330 so couldn't say how that'd compare

@highend666 Soulution gear is pretty damn good.  Better t9 get it discounted.  I have the 540 SACD player / Dac. Very HAPPY.  Excellent source.  My reference was the resonessence Mirus pro signature dac. I got the player below 10k which you rarely see. But I’m set as a source for life I run it through using my Melco music server. I’m in a great place 

What i call a bargain is a used Gryphon Diablo 300 for 7.5k

Boulder integrated and vinny rossi comes to mind. Solution is very very nice..up to the listener.