Auditioning amplifier gear: simultaneous auditions, online retailers you trust?

Hi folks,
I'm in the process of choosing speakers and amps. First, I get the speakers and try them out against another pair I'll buy here in Denver. Then, I'll return the pair I like least.

The next stage is to choose an amp which has the right character and power for the speakers I choose. I've never owned a truly hi-fi amp. state or solid state.

Some parameters:
* purpose is two-channel music listening
* budget $3k max; be nice to hit below that, say $1.5k
* exploring whether to go separates or integrated, hybrid tube/solid
* preliminary brands which have caught my eye: PS Audio, Schiit, Parasound, Rogue, Vincent, Peachtree
* present stable of gear (vintage): Adcom separates (535L 60w/ch. with GTP 400 preamp), Rotel RX-830 receiver (20w/ch)

QUESTION: My question is about how to narrow down choices. Some gear I can audition locally. Other stuff, I'll need to buy on the internet. So, some questions.

1. Hybrid/Solid State — Do you think I'll get a good basic sense for "tubes vs. solid state" by listening to any decent tube and any comparable solid state? For example, let's say I'm interested in Vincent vs. PS Audio but can only compare, say, Rogue vs. Parasound. I know these amps will have their own signature, but will I at least glean the basic difference between tubes/non-tubes?

2. Number of simultaneous comparisons. How much gear have you profitably compared at once? I am thinking I'll try 2 at once. I could put three on my card but then it starts to feel a bit ridiculous. Or maybe not?

3. Which internet retailers do you trust. I've seen good comments on Audio Advisor and Music Direct, mixed comments on Upscale Audio, Uptown Audio. If I were to have some gear from online dealers for a trial, who would be good?

Advice appreciated, including any direction to previous threads about this topic. I do search before posting my questions, but there's a lot of threads and some are old or not quite relevant to my question.
Thanks, Bob. I have done a bunch of listening to speakers and will continue. Same with the amplifiers.

@millercarbon I went to look at Synergistic Research about cables and it’s very hard to find a price list which simply tells the cost of the cables in an ascending way. I see many cables for $1k and more. That’s beyond my budget and comprehension at this point, and way overkill for the rest of my system. I know a lot of folks have $30k or more in their systems and I’m not heading there, yet. I may need to find another source of cables that are good but not mind-boggling.

Oh, and I'm not going toward LPs. I'm going CDs and streaming.
Thanks -- noted those cable folks along with what millercarbon suggested. Once I make the bigger decisions regarding amplification, I’ll seek out those cables. In general, I’ve found learned some things from Youtubes Hans Beekhuyzen Channel: (a) Why my new audiophile cable won’t sound better: (b) Audio Hygiene 1: Power cables (c) Why audiophile cables might sound better

But cables are down the road for me right now. I need to think about the amps and auditioning.
Hide45, You might want to include Anthem in your list. Also, I have purchased several items from Galen Carol Audio.
He is down in Texas and I am up in New Hampshire. Of all the on line dealers I have dealt with he is the only one who managed to provide personal treatment and attention at a distance. Check out his web site and ask a few questions. I guarantee he will answer you personally himself.