In terms of GPU Card to AVR, could be a bit unstable depending on non-active cable length (If were talking about 4K 60hz HDR with Dolby Atmos using 1 cable). I used to have a Monoprice active HDMI cable, the end broke but many few months later, I gotten a ONN active cable, it zapped my HDMI port on my GPU, fried my Motherboard and Power Supply. What I like to do is (It's a bit janky) but I found using 2 separate cables, 1 to the AVR (Audio), 2 to the TV (Video), is a lot more stable.
In terms of "bit-perfect" music playback and devices. It really depends on personal preference and device choice. . Your "old style" digital inputs could sound better than HDMI. Amirm did some tests with HDMI, you check it here:
https://www.audiosciencereview.com/forum/index.php?threads/a-deep-dive-into-hdmi-audio-performance.56/ . If I personally listened to music critically on my AVR, I would pick an outside USB DAC (via Analog) and use the "Pure Direct" mode. Maybe you prefer a digital-to-digital connection, you could get a outside USB DAC still. The best bang (for an outside USB DAC) would be the Topping D10S, it's got analog out and digital outs. In terms of improvement, technically, using an Outside DAC (Digital/Analog) is better than using the HDMI (Motherboard/ GPU) & Motherboard Digital outputs for audio. Would you notice the difference?, it depends on your ears. Maybe the HDMI audio sounds the same as the outside DAC to you.
If you got a GTX 10 series or newer video card, your HDMI goes out & have DVI still. DVI Dual link (Via DVI Dual-link to HDMI) can do 4k 60hz (YCbCr420 only I think). I found this out after I bought an expensive DisplayPort to HDMI adapter. I still use that adapter for video and use the DVI for audio.