I have used Y connectors over the years, never a problem.
People bring their preamps and phono stages here, we compare them to mine, sometimes using Y connectors, never a problem, everything sounds the same as when Y is out.
I use a Chase RLC-1 remote line controller to get volume, mute and balance for various units. No xlr. 4 rca in/2 rca out (identical front and rear from quad days). No one has ever been able to tell if it is in or out of the signal path. They can also work thru tape loops.
Your xlr equipment may have the advantage of a slightly stronger signal than rca's.
Cannot find a decent RLC-1 to buy now, current ones are missing the remote which is needed as no controls on the unit. they pop up from time to time, around $100.
This, ridiculously priced, shows the features