Warm Sounding Cables for Devialet

[Axel]

Then, maybe it's the ribbon tweeter on my ProAc Response D30R speakers?

However, before the Devialet 200, I had an EMM Labs Pre2 SE pre-amp and a Bryston 4B SST2 power amp (using the same sources) and never found it "bright" but now, on certain recordings (same CDs and FLAC music files), it sounds a little bright.

My ProAc Response D20Rs use the same ribbon tweeter and they never sound bright or harsh, in fact, on some tracks I give the treble a boost of 2 dB. So I doubt whether it's the ribbons that are causing your problems.