You could look at the 12BH7(A) instead of the 12AU7. The BH7A has slightly lower plate resistance (5.7 vs ~7.7k), high capacitances (2.x vs 1.6pF) and higher heater current requirement.
Others have indicated leaner clearer sound but that all depends on the circuit, operating points etc.
12BH7A has two main variants, although there's no denominator on the model number, one hass longer plates (GEC 1950s) which is now sold as the 12BH7A-STR and the other is a shorter plate variant. Slighty different sound - the STR version being clearer/leaner, the other (ie JJ etc) supposedly from other's accounts has a fatter sound.
Others have indicated leaner clearer sound but that all depends on the circuit, operating points etc.
12BH7A has two main variants, although there's no denominator on the model number, one hass longer plates (GEC 1950s) which is now sold as the 12BH7A-STR and the other is a shorter plate variant. Slighty different sound - the STR version being clearer/leaner, the other (ie JJ etc) supposedly from other's accounts has a fatter sound.
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A half decent 6111* will blow the socks off any "AU7", for size, linearity and quality, and there are 1000s still around.
I had some CV4034 NOS Brimar. (wire ended 12AU7).
Used them in a "brimar" circuit,- was totally underwhelmed although you can get them for a tenner a piece.
After subbing them out for the submin (with an essential tweak), I would never go back.
They are just what the effectrode guy claimed them to be.
6CG7/8CG7 / 8FQ7 is a good one to use, - real equivalent of 6SN7, and costs almost nothing, so I can't understand anyone wanting to use ECC82 for audio.
*You can also get the 6n16b-v gold gilded grid USSR mil valve for peanuts which apparently is just as good.
Good to distinguish between hi-fi and other uses - in guitar amps the 12AU7 is just fine as a voltage amplifier or phase inverter (important for the tone of the VOX AC30 for instance).
In hi-fi it might be useful to distinguish between the different tasks we might give a 12AU7. For example, I have played with NOS 12AU7, 12SN7 and 6CG7 valves as voltage amplifiers in preamps. The 12SN7s showed least distortion at higher anode voltages (around 200V) the 6CG7s just as good but at slightly lower voltages at lower anode voltages (100V to 150V), while the 12AU7s showed higher distortion at all voltages. Not a lot more distortion, just a bit more and if NFB is involved, then then the 12AU7's contribution to distortion might amount to nothing. As for sonics, choose your destination .... (Personally I like 6CG7s as mu-followers - very low distortion at convenient voltages. Once upon a time Ian Thompson-Bell had some good measurements of 6SN7 and 6CG7 mu-followers up on the net. Will one day try a 6111 as a mu follower.)
If we are talking phase inverters or driver stages, then the 12AU7 makes an excellent cathodyne or cathode follower, and a pretty good long-tailed pair. The same can be said for the 12SN7 and the 6CG7 - all these valves have delivered good results in these roles ... though none really have the grunt to drive big triodes like the 6336 or triode-connected KT88 to full power. There are other valves for that kind of work ...
In hi-fi it might be useful to distinguish between the different tasks we might give a 12AU7. For example, I have played with NOS 12AU7, 12SN7 and 6CG7 valves as voltage amplifiers in preamps. The 12SN7s showed least distortion at higher anode voltages (around 200V) the 6CG7s just as good but at slightly lower voltages at lower anode voltages (100V to 150V), while the 12AU7s showed higher distortion at all voltages. Not a lot more distortion, just a bit more and if NFB is involved, then then the 12AU7's contribution to distortion might amount to nothing. As for sonics, choose your destination .... (Personally I like 6CG7s as mu-followers - very low distortion at convenient voltages. Once upon a time Ian Thompson-Bell had some good measurements of 6SN7 and 6CG7 mu-followers up on the net. Will one day try a 6111 as a mu follower.)
If we are talking phase inverters or driver stages, then the 12AU7 makes an excellent cathodyne or cathode follower, and a pretty good long-tailed pair. The same can be said for the 12SN7 and the 6CG7 - all these valves have delivered good results in these roles ... though none really have the grunt to drive big triodes like the 6336 or triode-connected KT88 to full power. There are other valves for that kind of work ...
Not surprising given the pin outs and 8.4V heater. Not your normal tube-roller's dream
But for DIYers 
Seems someone on otlasylum has done a lot with the 6n16b and swears by them (although they're wire ended).
You mean 6n16b-v 6Н16Б-В.
There are a lot of variants
6Н16Г-ВИР 6Н16Б-ВР6Н16Б-Иmade in Moscow or Orel
They are cheap, available new, and almost the same as 6111.
The wire ended thingy is no worry you can get little PCB you solder them into, and then wire them in normally or make an adaptor.
(there is a tweak to make them run quiet)
I personally gave up with 12AU7 after my tests proved they were nigh on useless in audio, and gave a coarse unpleasant sound.
However as CF or split load phase splitter they are fine (eg in 7247/12DW7 use).