The bestbuy dude was not entirely wrong. Good speakers can start to be very revealing of a lousy front end. Low end receivers sound like ass for music. Flagship receivers can sound good but they cost a lot. You may be able to outdo the sound of a flagship receiver at around a 3rd of the cost with certain integrated amp and dac combos (for 2 channel music).
This is largely a hometheater/movie centric forum where receivers loom large.. I personally like receivers because i do a lot of my music listening in multichannel, but, i also have several purist pieces for 2 channel music. Try and get different opinions at audiogon, stevehoffman, etc as well which may have a higher density of 2 channel hifi centric guys. Who knows...you may even end up being a tube amp kinda guy or something...Have fun while you're figuring out what works for ya.
Be careful, there are a lot of audiophools on Audiogon and Steve Hoffman has definite tendencies to audiophilia. Be very careful of subjective opinions. It really is your speakers that overwhelmingly determine how your rig sounds in any given environment. The maxim holds, that if you don't like the sound you are getting, then go speaker shopping. If you are a DIYer like me, then it is modify your current one of design and build some different ones. It really comes down to that, with the amps and receivers it comes down to reliability and longevity. It seems to me receivers do have longevity issues, and do have trouble powering speakers that present difficult loads.
So if you have a two channel system with low impedance speakers, then adding a beefier power amp can be an asset. This requires using a receiver with preouts, or using a pre/pro and external amps. I personally don't use receivers, as I'm wedded to my power amps.
I think music only systems are becoming increasingly limiting, as so much music on offer comes with a picture now. So all my systems, even my two channel, has a TV screen. That pushes you in the receiver or pre/pro direction.
Lastly it is nonsense that a good theater system can not be a good music system. That nonsense continues to be propagated. If a theater system does not reproduce music really well, then it is a lousy theater system period, and will more likely than not have speech reproduction issues and other shortcomings. A good theater system should be a first class music reproducer, to which a screen has been added.