An amplifier and a lower volume made a difference. AKG and Sennheiser proved they could make pleasant sounding 'studio' headphones. The DT250-250 also sounds pleasant yet detailed enough for a critical listen.

Sony studio headphones I had were either bright or harsh sounding. The CD1700 I once had though did sound smooth yet detailed.

It is strange. The V6 was not even uncomfortable. 

Dug them out of the closet again because I was bored. I threw some Brainwavz HM5 pads on them and threw in a set of circular dampening foams I had from another set of earpads (picture something like the MrSpeaker Dog Treats).

Much better now, listenable; I could use these in a pinch. The edge is taken off of the treble a bit and it seems the pleather HM5 pads have helped fill in the low end and low mids. That odd 'plastic' sound still rears its head on some tracks, but not as often. I've also found that listening to them at lower volumes than I would typically listen have produced much better results (I think this was also mentioned earlier in this thread); everything sounds more natural. I think the issue with these is since they lack low bass, you are tempted to turn up the volume to compensate, and that's when the highs get sibilant and unbearable.

It was often reported that the DT250 velour ear pads had a good effect on the V6. Also apparently you can fill the cups with absorbent material to make the sound fuller.

Things is, the V6 gave me headaches due to its sound. I would not recommend this headphones without including, "can sound harsh and bright, mind the volume". I just detest Sony for making this headphone sound the way it can sound. Sony knew better knowing Sony did know how to make good headphone drivers before the MDR-series.

The old Sony DR-5 sounded like a K701 without glare. Just saying...

I remember reading about the filling the cups mod back in the day, never got around to doing it, but could see it helping as it did similar things to the Denon Dx000 series when the modding scene was pretty active for those. I did try the DT250 pads at some point in the past and remember it not changing the sound much but only changing the comfort.

I'm okay with how it sounds now with the Brainwavz HM5 pads and the felt discs inside. I might toy around with adding another Doggie Treat to tame the highs a bit more when my Alpha Dog comes back. I'll report back when I get a chance to do that. The drivers themselves are pretty fast and seem to be capable of more than Sony has extracted from them in the current stock V6 form. I could see them benefiting from an improved enclosure a la the T50rp:Alpha Dogs, but the ceiling is likely much lower for these and may not be worth the time or money.

They probably still won't get much head-time at home competing with the Alpha Dogs, HD800, and MA900, but could see myself using it when I'm outside as a change of pace from my IEMs. I'd call it a success as they were collecting dust in my closet so any use is a win in my book.