I'll have to give them a longer listen. Right now I'm using a Sophia 6sn7 pair + sophia mesh 274b. I'm getting Psvane cv181 (6sn7) treasure mkii / shuguang natural sound series cv181-t (6sn7) / shuguang replica series we6sn7 pairs in the coming weeks. Currently for pairs I have Sophia 6sn7 and 6sl7 / NOS "bad boy" 6sn7 / melz 5 hole anode 6sn7 / iha-1 stock raytheon I'll do a write up for all of my pairs, when I get my order from China. I guess my memory of stratus is too old to really give specifics. I'll only say, it didn't personally blow me away like my Dennis Had fire-bottle did (and this why I bought iha-1). I only heard ZDS at a meet, so I'm giving only the aspects that really differentiate the two. ZDS is a dryer amp, in that it doesn't sound very tubey, almost thin... It's not a great pairing with hd800. ZDS has much greater soundstage than iha-1, and that's not a knock on iha-1. ZDS soundstage is almost unnaturally big. Very airy! iha-1 wins in microdetail (resolution), it has a more wet sound, instruments have weight and a liquid sense to them. Although, being liquid doesn't smooth anything out, it's still tac sharp. I'd say it has above average soundstage, just shows how crazy ZDS is in that area. Iha-1 is a great pairing with hd800 / hd650, obviously not enough power for something like my he6. For my personal tastes, and being an hd800 lover, the iha-1 is the no contest winner in my book. Oh, and if you like tube rolling, iha-1 is better than ZDS in that regard.