My Oppo is a bit too bright

Simao get a tube DAC , this will give you full sounding, bloom, and romantic feel.Black ice from Underwood Wally...

Audiomirror trobadour, Teajay Orchid recommendations.This are all good Tube DACs , your budget will dictate.

Try feeding an external usb drive directly into the Oppo playing .wav files. That is how it sounds best in my system; beats spinning a disc and .flac format. Never found the 105 to be bright under that configuration. If anything, there’s a slight (artificial?) smoothness and maybe a slight pronouncement in the lower frequencies, but not bright.

I agree with some of the other posts that suggest the OPPO's use of the ESS DAC chip is potentially the primary reason your impartial listeners found the sound a little harsh. This is not contradictory to the fact the OPPO analog output is very good or that the player is an excellent product and outstanding value. Many people like the strengths of the OPPO analog output and of the ESS DAC chips.

But if someone feels there is some harshness or listening fatigue which outweighs the other parts of the ESS-based DAC sound, then a very common alternative are the AKM 449X-based DACs because just like the ESS the AKM chips are used a lot. These also produce very good sound but along with potentially sounding less harsh or fatiguing there are other aspects that will sound different.

Obviously this is a generalization of implementations of the ESS and AKM chipsets, and there are some products where this characterization doesn't strictly apply, but on balance I feel this is a reasonable starting assumption without additional information about the DAC design or without having heard the DAC itself.