Which would you choose; Pass 250.8, arc 75SE or luxman m900u?

OP: while I appreciate your seeking advice about 3 specific brands from the forum, it seems like you need to audition them in your system. All the banter here will not resolve the ultimate question. 

@guyl, ARC and others design their gear to work synergistically together. So I’m not surprised you enjoy your ARC combination.

An owner endorsing gear they own is simply bias confirmation. That in of itself should trigger a red flag in the minds of prospective purchasers. Are such endorsements valuable? Sure they are. Are they more valuable than anyone else’s input? I doubt it. 

For the enlightened, perceived abuse of another member is usually the reason why posts are called to the attention of moderators for removal. 

@guyl, +1 for your impedance matching insight. I have a new thread devoted to that topic (again).

Yes, manufacturers often voice their gear together. Once, the late John Ulrick of Infinity Systems and Spectron Audio fame told me to keep my Dunlavy SC-IVa’s with my Spectron Audio Digital One Class D amp because John Dunlavy voiced his SC speakers with that amp as one of his go to amps. 

@hk_fan, so dealers are D-bags yet owners are not for engaging in the same activity? It seems to me that the manufacturers and dealers who engage in self-promotion are not guaranteed any product sales for doing so.  

I find nothing wrong with a dealer or manufacturer making a contribution to a thread if they feel it’s warranted. Even if such posts might be perceived as blatant self-promotion, it’s up to the OP to evaluate the content of each post, as well as the reasons why such info might be discounted. Most here are adults, so I’m confident that everyone can discern the content of each post for what it’s worth.

And I’m sure the OP (or any other causal reader) can discern that, too. You seem to discount the power of endorsement by an owner having spent hard-earned money on their gear. 

David, I simply recommend taking all the input to heart. And factor in bias to the extent possible. The closer the owner’s gear setup is to mine, the more I’m likely to weigh that contributor’s input favorably for the reasons set forth below.

Here is the problem as I see it. We all have different listening environments. We all have different gear setups, ranging from power conditioning (or not) to power cables to IC’s to gear and speaker cables (if needed for those not having active speakers, like I do for my ATC SCM20-2A’s which I love owing to their compactness) to speakers.

When I make posts to threads about specific gear, like I have about Jay’s Audio CDT2 MK2 transport on TeaJay’s thread, I list all the gear and accessories used in my opinion. Regrettably, the biggest factor, the acoustic space, is left out for obvious reasons.

Without wanting to engage in regurgitated info already posted, the OP will ultimately want to select one or two of these amps for audition in his home system. All we can do is provide informed guidance to him.