which Brand of Reciever produces the Best Audio?

The vintage sound is no longer considered the "best" audio sound. Best audio for HT in my book would be Meridian,then Cary...any of which would be 5 figures worth of HT audio equipment

Modern "sound" is less fuzzy and warm than vintage sound, less "round", and probably more truthful than the vintage sound you love and that your ears have grown used to. Some of what you are hearing in your current system is, frankly, coloration, but that is part of its appeal for you. It may not be "truthful" or truly transparent and detailed (the modern holy grails of audio) but it is forgiving and easy on the ears - it's also what you like. The price you pay for that smoothness is slightly rolled off highs, a bit off extra mid-bass to midrange warmth...which results in a lack of transparency and detail, which isn't necessarily a bad thing with HT and digital audio recordings, but its not the current "flavor".

Also keep in mind that many HT fans have never heard high quality high end audio only rigs, much less mellow vintage components, so they have no idea what sound you're aiming at.

It seems to me you don't necessarily "want" a SOTA, much less a modern sound, so although they don't sound vintage, gear from Arcam, McIntosh and B&K, components known for their dynamism and warmth, are the way to go. NAD is also pretty good but a step below the above.

The Denon 7.1 channel digital receiver, model AVR-1507. Some told that Denon is the Mercedes of home theater receivers.

The Yamaha RX-Z7 sounds wonderful for a receiver as does the Marantz SR8002, which is now out of date. If I were to choose a receiver, it would be the Z7 because of it's attractive price and real-to-life power it delivers. Of course I do like the Arcam and Sunfire offering's as well. But, then you get into the realm of why not just buy separates.

I found a Sunfire TGP IV or V (with HDMI) produce sound that rivals many separate preamps including tube units. I do not need HDMI so I found a TGP IV for $550. It has a super tuner and a very nice phono preamp. It retailed for over $4000. Mine is paired with 2 PS Audio Delta 250 monoblocs that I found for $1100. I could always add more amps and speakers for surround. The sound does have a slight warm tendency which is very pleasing to listen to. I know what you mean by the digital sound and most new recievers sound that way. I used to run my video through a component switcher to my projector and my audio was an all tube 2 channel setup. The TGP IV is much simpler to operate and comprises very little over tubes. But that is another way to go. I have a mint Marantz 2270 with Polk 10 speakers so I can compare quite easily to the sound you are looking for. It is hard to compete with the 2270. Once you turn it on you keep finding excuses to listen to one more song because it was designed for music and not specs. Good luck in your search.

Audition the NAD 785 if you can.