30dB of voltage gain is slightly higher than average, while an amp with around 24dB gain may be more typical - but the difference is only 6dB, and that won't buy you much additional range on your volume control (very little, in fact). The real issue is the volume control not resolving the low-end of the attenuation range well (combined with the high gain of the preamp), but there isn't much you can do about that. If you are going to change amps, try to find one closer to 20dB gain if possible, or at least try to maximize the gain difference.
Another option is to use a truly transparent signal attenuator designed for use in high-performance audio systems. By strange coincidence, I happen to be making just the thing ;-)
Best regards,
Steve McCormack
SMc Audio