This is impossible to answer due to too many variables, but keeping it general...
If you're using this setup strictly for HT (where sound quality is not the only focus) I would tend to doubt the preamp section of a $1500 receiver will make a huge difference over that of a $500 receiver when paired with a good amp. That said, using the pre/pro section of a cheap receiver (or even a more expensive one) in front of a good amp is a bit of a waste since you likely won't hear all the benefits that amp can bring. I think it's all about balance, and in audio the chain is only as strong as the weakest link. If you care enough about sound to invest in a decent amplifier then your long-term goal should be to pair it with a decent pre/pro, so starting with a cheap receiver as a pre/pro could make sense if upgrading to a better pre/pro when funds allow is the ultimate goal.
The problem with a more expensive receiver is a lack of flexibility. You're stuck with the amp and pre/pro packaged together, and using the pre ins/outs when you upgrade to a better amp or pre/pro seems kinda silly to me if you're spending a good amount of money on the whole unit. At least with separates you can sell off the piece you're looking to upgrade, which can be a nice benefit especially on the pre/pro end since formats/connections/DSP will undoubtedly continue to evolve.
Anyway, I don't think I answered your question but I'd be careful about spending a lot on a HT receiver because you start to run up against the cost of decent quality separates and their inherent advantages (separate/beefier power supplies, better shielding, flexibility, etc.). Best of luck.
If you're using this setup strictly for HT (where sound quality is not the only focus) I would tend to doubt the preamp section of a $1500 receiver will make a huge difference over that of a $500 receiver when paired with a good amp. That said, using the pre/pro section of a cheap receiver (or even a more expensive one) in front of a good amp is a bit of a waste since you likely won't hear all the benefits that amp can bring. I think it's all about balance, and in audio the chain is only as strong as the weakest link. If you care enough about sound to invest in a decent amplifier then your long-term goal should be to pair it with a decent pre/pro, so starting with a cheap receiver as a pre/pro could make sense if upgrading to a better pre/pro when funds allow is the ultimate goal.
The problem with a more expensive receiver is a lack of flexibility. You're stuck with the amp and pre/pro packaged together, and using the pre ins/outs when you upgrade to a better amp or pre/pro seems kinda silly to me if you're spending a good amount of money on the whole unit. At least with separates you can sell off the piece you're looking to upgrade, which can be a nice benefit especially on the pre/pro end since formats/connections/DSP will undoubtedly continue to evolve.
Anyway, I don't think I answered your question but I'd be careful about spending a lot on a HT receiver because you start to run up against the cost of decent quality separates and their inherent advantages (separate/beefier power supplies, better shielding, flexibility, etc.). Best of luck.