Quick little review -
Some quick impressions of the opamps first,
1) Stock opamp is the OPA2134 - widely regarded as on the darker side, these have the narrowest sound stage/imaging of the three. Instruments bleed into one another and sounds muddy overall.
2) V6 Classic open the soundstage substantially, and imaging is much more precise. Everything has its own space in the mix. Instruments like guitar and vocals that are panned near the center of the mix are pushed closer to the center, making a more intimate experience than the Vivid. Treble is rolled off compared to the Vivid; cymbals lose their sheen and snare loses its edge. Mids like guitar and vocals are boosted up, becoming the centerpiece of the song. Bass is loosened; eases up and doesn't demand attention. Overall the sound is more relaxed, less realistic than the Vivid but still leagues better than the OPA2134.
3) V6 Vivid widen the soundstage more than the Classic. Imaging is still as precise also. Depth of soundstage increases; intimacy is lost at the gain of a wider and all-encompassing soundstage. Treble is back compared to the Classic, cymbals sound pretty realistic (maybe as good as being behind the kit itself
). Mids are no longer the feature, the Vivid is a mirror of the source material and the rest of one's audio chain. Bass is tight and accurate, and a little more present than the Classic.
I used a Topping D50 DAC feeding an Audio-Gd Fun Preamp which uses one opamp in the output stage. I found changing the opamp has a big effect on the sound going throughout the chain.
Impressions with a couple headphones,
1) Koss ESP/95X - The Vivid shows the effortless natural reproduction capabilities of this headphone, which can be too much if you are working at your PC as the sound is so detailed. The Classic makes the sound more of that classic (
) tubey, mid-centric relaxed sound which is what I've been using most of the time so far.
2) Grado GS1000 - If you've heard these you might know they have an excessive V-shaped signature, with over-exaggerated mid-bass and treble. The Vivid brings more of this to the table which I found too much. The Classic, however, breathed new life into the GS1000 as it tames the bass and treble, while boosting the mids just enough that the V-shape is no longer unbearable to listen to
. It also brought the massive soundstage into line and let me enjoy a pair of headphones that had been collecting dust for the better part of 5-6 years
.
I should also mention both opamps have 100+ hours on them. I left the opamps to burn in day and night, listening occasionally during the day.
The Classic sounded thin and lifeless right out of the box, as others have said. I listened to them for the first few hours, and after hour 4 I noticed their signature sound starting to come around. After 24 hours I couldn't notice a difference, and they've probably had ~200 hours at the time of this post.
The Vivid sounded -- really -- bad out of the box, really not good. The bass was mushy, treble was muddy and totally whack, but I knew what was coming so I kept them burning in night and day. Again, after 24 hours they were getting there in terms of soundstage and treble extension, and at 100 hours they are pretty damn good. I don't know if I could tell much of a difference between hour 24 and hour 100+.
I've seen the SparkoS recommended, I have zero desire to check them out at the moment, as I enjoy comparing the 2 V6 opamps and they are leagues ahead of the stock IC opamp that I had been using for years. And according to some, they can only get better
.