Many years ago, I asked a service technician about the 6N23P for my 6922 preamp. Here’s his response.
I’m glad you asked me because the 6N23P-EV (in our alphabet) is not the one to get. The 6922 drop-in replacement is the straight-up 6N23P. The EV versions have too-low cathode resistance that will draw too much current in a 6922 circuit and lead to a lack of headroom that compromises dynamics.
The regular version is dead-on. Many people get it wrong and think the EV is better, which is true in the case of 6P14P (EL84 power pentode), but is not for the 6922 replacement.
Since you’re asking about an amp, not a preamp, it might be different.