Help Finding my system bright...

Room acoustics can make or break a system... Otherwise some
Extreme Electronic equalization injected would be the only other way to help flatten out the mids and highs to balance out to get back the missing lows.

You can chase the dragon with some thicker copper power cords, and colored interconnects, speaker cables etc... But even all this will just take baby steps and not totally satisfy or eliminate your issue.

I am guessing your plinius is an integrated amp, I have suggested in the past the Mcintosh integrateds do help a lot in these cases as they are rather warmer sounding pre section and amps all in one with a good 5 band equalizer that will pretty much fill out the sound of any speaker you throw at it.

Plus I have read the totems might be a bit difficult load to drive via efficiency and Impedance character, so if it drops down really low like 2 ohm some integrated amps might sound thinned out trying to handle the load or matching up easily. So without getting into a room overhaul, you might want to go the route of a integrated as stated above, no super cheap tweak is gonna do it, or a few hundred more in cables. Not to say it can't help but your kinda looking to just solve it I would guess. Only other free thing to do is some serious evaluation on speaker position, back forth, further apart, trying to get them on another wall etc...

Well then I echo the question above, what changed to now make you feel its bright? Realistically I have had audioquest designs back in the 90's… they were always a bit Grainy and harsh with some components, mostly due to the multiple solid conductor litz type arrays the speaker cables seemed to use. At the time Kimber and Audioquest along with monster and MIT, straightwire, wireworld were mostly available at most of the higher end home theater stores when they started all changing over from 2 channel to multi channel focus…

However again not sure cables will completely solve the problem, it seems more like a room and or synergy of the components issue, and if in fact the Plinius you list above is a standalone amp than what is the preamp used? This will have a bigger effect in many systems tonal balance than the amp. Or are you just running the bel canto straight into the amp with its onboard volume control or something? If so that is your issue, you will need a full frequency preamp to add body back to your digital sound helping eliminate the "Digititus" that many experience running direct eliminating a good preamp. Has more to do with impedance and just harmonic problems that make music lose that full organic feel.