South:
Are these perhaps 7025 tubes (not 7024)? If so, then they are a type of 12ax7 (ECC83) that may or may not be lower in noise than a typical 12ax7. Real 7025's have an added coil that would theoretically decrease noise, per my basic understanding.
If this is the case then what do you want more of in the sound?
7025's were commonly used in the phono sections of vintage preamps and I have ended up using either Telefunken of Amperex 12ax7's in there place (depending on the sound that I was looking for) with excellent results (Tel. for smoothness and Amperex for detail). Some Mullard constructions are also nice, but many are not and I have forgotten the Mullard types that I used to prefer, over the years (just remember that their plate construction looked way different than that of Amperex/Telefunken).
Anyway, never heard of a 7024.