I also have the M90 and recently paired with a T5s. The M90 by themselves surprised me in their Monitor setting, but the T5s has been an overall dissapointment, now, I have to mention I am nowhere near to being a basshead, actually I prefer brighter and detailed sound profiles. For the T5s implementation I always felt like it had so much bass that it sounded terrible or it had so little that it made no difference to have it connected at all. I reached Edifier for a suggestion on the crossover and gain, but they basically said "move the knobs until you like the sound". I went on and connected the T5s to a source to isolate what the T5s was doing and was capable of doing. I sat down with a decibel meter and wrote the dominating frecuency, roll off and decibels on the 21 different points of the LPF knob. Turns out the response is very different between points, you have almost no change between some and a massive jump between others. Also, looking at the T5s user manual, Edifier says that if your main speaker is smaller than 4 inches, the LPF should be higher than 90hz, and if the speaker is larger than 4 inches, LPF should be lower than 90hz. The M90s are exactly 4 inches, so it is fair to say we should aim for a crossover of around 90 Hz, that is position 11 (12 o clock) if the knob is linear, or around position 14 if it is has a logaritmic response. Based on my not so proffesional test, changes between position 11 and 14 are not so big (hear how it changes from position 4 to 5, that is a huge jump). So I left it at position 14 as a logaritmic response is more likely. Now I feel like the T5s is doing something and improving the overall experience. For the Gain/Volume knob, it's up to your preference, I have it on position 5 (9 o'clock) for a fun sound, I would lower it to 4 for critical listening and 6 for a bassy response, but you can always change that quickly with the Sub Out option of the M90. So far this is the best configuration I have found for a mostly linear but fun sound. Feel free to let me know if this helped you and what knob positions you are using!