I have just made the (possibly final) upgrade to my system: I bought an Esoteric K-03 XD and an N-03 T. The latter only arrived at the end of last week. I am very happy with the sound quality; the streamer is still getting better and better. I am using ROON installed on a dedicated NUC; both streamer and NUC are connected to a Netgear Ethernet switch.

I was thinking of finishing the upgrade by having a look at USB and speaker cables. Other interconnects are solid silver XLR cables I’m quite happy with.
The streamer is connected to the DAC in the K-03 XD with an Audioquest Carbon USB cable. When I bought it to connect a Melco N1 to an Esoteric K-05 X, I could hear a subtle improvement in sound quality over a generic USB cable, somewhat to my surprise. Could further improvements in SQ be gained by using a different USB cable? Does anyone have any suggestions considering the units it will be connecting? I would be reluctant to spend much more than about £500. I had a look online at the Oyaoide Continental, which certainly seems quite carefully made.

My Bryston 4 BSST 2 is connected to my PMC Fact 12s with 6mm copper van Damme DIY cables terminated with Furutech plugs. At least in terms of price, this could be seen as a bit of a mismatch with the rest of the system. Would it be best to look into upgrading the speaker cables first? My local hi-fi dealer has a demo pair of AQ Robin Hood cables. He also suggested Inakustik LS-1204. Does anyone have any experience with these cables? Or other suggestions?

Many thanks