Rolled my 2A3 spares, I haven't heard them yet with the ECC40 input and it's good to take a break from AVVT. Ken Rad black glass One of my absolute favourite with the Stratus. Fullest low end in terms off impact and weight but lacks control absolute. Nice for slow bass heavy music. Mid bass is accentuated and on the warm side. Very mid centric without being warm. Where in the Stratus I would have said bass its party piece in the Stellaris it's the mids. A bit of grain only when compared to the best with fantastic tone, certainly not neutral but hugely pleasing to listen to. Presents as much mid range detail as you can throw at it. Treble is a bit shy and on the darker side but all the fine detail is present even if at a lower volume than I'd like. Soundstage and depth is about average, nothing spectacular, layering is exceptional but that's more the Stellaris doing its thing than the tube. Strings lack bite, the edges are more rounded than I'd like. This is great for a leaner configuration or headphones such as HD800. In the headphone world this is the HD650 of 2A3. Sylvania dual flat plates. These were around average on the Stratus but shot to the top on the Stellaris. Low end if very tight, extended and controlled but lacks the fullness of the ken rads. Very close to neutral while still musical and quite similar to the single plate or AVVT for tone. Still I'd prefer if I could have the Ken mid range on this. Great crunch to instruments and bite. Dynamics are well above average especially compared to the kens. Larger sound stage as well with better layering and depth. Sounds do tend to pop out of nowhere at absurd angles. Extremely balanced across the frequency, top end is highly detailed though to be critical some edges are not as fine as they could be but never coarse. The only downside is slight shoutiness in the upper mids on certain tracks and on occasion the timbre in the mids is somewhat plastic but only on critical listening. I prefer to actively listen on this tube where the Ken Rad is doesn't call as much attention to itself. KR 2A3 A perfect blend of Ken Rad and Sylvania taking the best traits of both. There's something absurdly musical about this tube, transients are seriously natural. Liquid. Low end is fuller than Sylvania but not to Ken Rad levels. Bass is well balanced and lacks ultimate focus. Bass can sound slightly loose but never boomy. Mids have are slightly warm and grain free, great tone. Edges are a bit rounded and strings don't have as much bite as Sylvania but it's a level where I can't complain and works well overall. High end is detailed, has good presence even if slightly soft. Soundstage and depth just above average but nothing exceptional. For a modern tube you can buy today this gets my approval even if absurdly expensive. Not for detailed freaks, more to kick back and relax. All three tubes are dead quiet on the Stellaris, I couldn't tell if the headphones are plugged in or not. Can't go wrong with any of them and you'll hear the DNA magic with any. Can't say the same for the stock tubes. AVVT Mesh These hum, some worse than others. I've tried 6 pairs, all of them have a low level hum that can be heard during quiet passages. Not an issue during playback and after an hours or so it dies down but it's still there. I want to get another 2A3 amp just with AC heater just to see if I get the same issue. I can use the -6dB setting on the Stellaris and that fixes it but it also reduces the dynamics. Still better than all the other tubes but knowing I'm not using their full potential is a turn off. Seems to be an issue with DNA amps as I've had the same behaviour with the Stratus.Only an issue with sensitive headphones like senns. 95db and lower should be fine. While listening to the other tubes I missed the crazy instrument separation these are capable of. Low end is full, tight, balanced and fully controlled. Soundstage is the largest of the bunch and only 300B tubes especially Elrog can outmatch them. Depth and layering is epic. Tonally these are between the Sylvania dual flat plates and KR, they retain the musicality of the KR without the rounded edges and the neutral tone of dual/single plates. Detail monsters with the second best being the mono plates. Best once fully warmed after one to two hours. Macro and micro detail cannot be matched. Overall it's a highly detailed tonally rich neutral sound that also comes as relaxing. It's as purrin said about having a 700hp engine cursing on the highway. Their only fault is the damned hum as it takes away the black background. I urge everyone not to buy these unless you're running a TOTL amp with top components and everything else in the chain sorted to the point were the output tubes are the bottleneck. Putting these on a mid level amp is like turbo charging a trabant. These on the Stratus were great but truly shine on the Stellaris. Also be weary of any AVVT tube with the golden AN markings. At first AVVT made tubes for audio note and there were quite a few issues as in blowing up, some still surface the market. I've seen tubes marked for destruction by vaic that were sold as NOS. Best to only get tubes made after '99 with serial number greater than 4500.