Upgrade from Denon X6700H?

Suggestion needed on receiver/Amp upgrade. I have a 5.1.4 living room theater which I'm using for Stereo(30%), HT(40%), and gaming(30%). I feel that the median frequency is a bit insufficient. Recently, I have a budget to upgrade the system mainly focusing on the receiver/amp.
My existing setup is:
Denon x6700h, Klipsch Forte IV (LR), the center is Klipsch RC-64III, the subwoofer is SVS SB-16 Ultra, the surround is Klipsch rp-600m, Klipsch PRO-180RPC(Atmos), 85X95J(TV).
I'm using an OPPO 205 as the media player to play UHD movies and CDs. Also, XSX for gaming, and TV for streaming.

I have about three ideas for upgrading now
1. Because the OPPO 205 has a DAC and it can be used as a pre-amp (with RCA and XLR outputs), if I configure a HIFI amp, the 205 uses HDMI to connect to 6700, which is only used when watching movies, and RCA or balanced output to the HIFI amp for music. In this way, I only need to open the 205-HIFI amplifier for music. But my question now is whether the cable of the subwoofer needs to be plugged and unplugged when I want to do music and movies (because music skips 6700), and the second is that it also loses a lot of EQ possibilities.
2. Add one integrated HIFI amp, 6700 for movies (HIFI integrated amp is used as a pure amp for L+R), and HIFI integrated amp for music. But there is still the problem that the subwoofer needs to be plugged and unplugged.
3. I also consider whether to directly upgrade the 6700 to A110 or 8500HA or even JBL's SDR-38 (but it only amplifies 7 channels, so it also needs an amplifier, and the price is a bit high). I don't know if it is necessary to equip a HIFI amp in this upgrade plan? I would also like to ask if the sound quality will be affected after the AVR is involved in the HIFI system? Then because Denon has no balanced input, it can only use RCA. Not sure if RCA is more disadvantaged than balanced connectionin the case of short distances?

I know my questions are a little scattered, thanks again for the guidance!