Topping D90LE as dac/preamp rca to sub + xlr to mains gain problems

[Chibrax]

Hello,
I have not seen this depicted after a few hours searching online and on ASR and was quite intrigued that it does not happen to more people.

So here is the problem, I stopped using XLRs to my amp (crown XLS 1502) and rcas to my sub (Emotiva SE12) because I have a gain matching problem and when I play with the volume of the preamp the implementation is messed up (it just holds up at my preferred listenning volume). And it evens makes the sub dissapear at low volumes or too loud at loud ones if I try just adjusting the gain of the sub up...

Signal path I use for now that works well (sub and speakers volume changes work at unison) :
TV optical or pc usb > Topping D90 > rca to emotiva sub in > rca out from emotiva sub (using the sub for bass management et hp filter) > crown > speakers

While Im way more satisfied with this solution than having perfect implementation only at one favored volume Im still annoyed by the fact that I cant use my gear as I intended.
The question is what are my solutions to getting back using XLRs for my mains (what is the purpose of a balanced dac and amp if I cant....) without having the aforementionned issue.
A buffer for the rca would have to be like 10db to match XLR outs ? what are the most basic/transparent solutions available to me.

 

[MaxwellsEq]

You probably need to measure what you are hearing using a calibrated microphone.

I've no personal experience, but many on here are very pleased with https://www.minidsp.com/ products.

 

[Chibrax]

You probably need to measure what you are hearing using a calibrated microphone.

I've no personal experience, but many on here are very pleased with https://www.minidsp.com/ products.

I am sure of myself changing the volume on my dac doesn't change the volume on the amp and on the sub the same way there is a difference in input gain and it shows....
when I go full rca to the sub and use the sub rca outs I have no problem...
The crown can do HP on its own I cross it at the same point as the emotiva rca out when I use xlrs...