Advice on Upgrade

I agree an integrated makes more sense at this price point. When you say the HK isn't musical enough what do you mean? Is it thin sounding and overly detailed or maybe too warm and not detailed enough? If the former there's a Hegel H70 for sale here that would perhaps sound more full and natural. If the latter there's a Bryston B100 that might be worth exploring. The Sim is probably a good choice too and may reside somewhere in between these two. Parasound is making good stuff too as well as Marantz, although the latter probably skews a little to the warmly detailed for better or worse. I'm sure your speakers will let you hear the benefits of whatever you end up choosing. Best of luck.

I would describe the sound out of the HK as thin without having any body. I am looking for a rich yet detailed sound. My thought was that I would be better off, and get more for my money, with just an amp as the Oppo and the Bryston can be used as pre amps. I know it may be taboo but the tone controls on the Marantz piqué my interest though. I know I could try the Marantz from Crutchfield and return it if I don't like it, but I hate doing that. I find that it's no use to even go listen to gear at a dealer even if I could since all the ancillary gear and the room is not the same as mine. Decisions, decisions.

With your current selection of components, I also think a high quality integrated is your best move. Makes like Creek, Musical Fidelity or Arcam. Many can be found on the used market. Don't confuse these with mass consumer integrateds, these units have balls.
After that you can think about a loudspeaker upgrade and then later a poweramp using the integrated as a pre-amp. .