I'd say stick with the design as-is.
The one unarguable advantage of a "balanced" amp is that the separate contacts of the 4 pin XLR or dual 3 pin XLR connectors eliminates the common ground contact resistance of the TRS plug/jack that results in increased crosstalk.
So if it's not too late in the game, I'd suggest replacing one of the two TRS jacks with a 4 pin XLR. Sure, pins 2 and 4 would still need to be taken to a common ground point, but the resistance of a good solder joint is much lower than the contact resistance of the TRS plug/jack. HiFiMAN is doing this on their HE-6 amp.
I was also going to recommend the same at very least as an ergonomic convenience to HE-6/K1000 owners or others with 4-pin XLR cables.