6H23 tube Ya or Na ?

I've heard this tube is a great replacement tube for the standard 6922.I own the modulus 3A ad ARC Vt100MK11.Has anyone heard great improvements with this tube?
thanks mike
I have a set of these tubes in my Modulus 3A that I got from Upscale Audio. They sound fantastic! They are much more dynamic than the stock tubes although maybe not quite as quiet, but not near as noisey as NOS tubes. I have compared these tubes to NOS tubes in my unit and I prefer the 6H23's. I only paid $25 each for them. I highly recommend this tube to anyone that has a Modulus preamp.
I have used them in an AI Modulus also and they are quite dynamic, quiet, non microphonic and very long lasting. While other NOS tubes last at most a couple months, e.g. Telefunken, the 6H23 still test fine. All in all qite a bargain.
Mike I replaced the tubes (Sovteks) in a friends Mod 3A with 6h23U-Eb's (the "U" is upside down) from ATSI tube and they have been running strong for the past six months. I also gave him a matched pair of Siemen's PCC88's (7dj8's), but cannot remember if they are used in the line or phono stage (had it all sorted out back then though). They are available as low noise/low microphonic "picks" for $45/mp. I will be listening to the system over the holidays myself, but he says that it has never sounded better (he listens to 99% classical on an LP12). I picked up a matched quad (for a rainy day) and another pair for my use and find them similar to old Siemens E188CC's and E88CC's when used as an input tube in my SET amp. My amp does not run the input tube very hard and it took 35-40 hours for the bass to kick in with my setup. The soundstage is not as forward as NOS Amperex/Mullard/Philips tubes (again in my setup), but I really like the tube for classical music as it sounds very realistic (kind of a mid-hall sound) and it is not rolled off @ the frequency extremes).
I tried the 6H23-EB's that ASTI sells for $45 (matched pair) in both the line and phono stages of my Mod3A. They are quiet, and long lasting--just as others have noted. They turned out to be too bright for use in both line and phono sections in my system, though. I kept the 6H23's in the phono section (because that seems to be harder on tubes) and went to NOS Amperex E88CC's in the line stage.

I agree with the other poster on this thread who mentioned that the Amperexes tend to be a bit forward.

The Amperexes' smoothness, transparency, detail, and front-ish perspective in the line section combine well with the 6H23s' dynamics and mid-hall perspective (also said elsewhere) in the phono section.

What other folks have said about the 6H23 in the Mod3A is pretty much my experience--other than I find them to be too bright for the double section dosage. I noticed the the VTS tube list mentioned this in the notes for the 6H23's vis-a-vis the Mod3A.
i'm not using a modulus, but i am running 6h23eb's in my sp10. tonally there is no difference from my older sovteks. the 6h23's are a bit smoother and in my system just a tad noisier - they will not solve brightness problems if you have them. can't tell about longevity - in my amp the line tubes last, seemingly, forever.
They have also worked well in my BAT VK3i which uses 2 per channel in the line stage. Can't comment on longevity as the BAT is very easy on tubes, but they sounded fine.