It will probably sound better. I've always thought Krell preamps were a little underrated, but the KBL is old. The KAV, I feel, is a bit more modern sounding. If you like the Krell sound, I think you'll be happy.
Not to get off topic, but if you like the KAV preamp, you may like the matching KAV 250 amp. I used to have one and it was a lot better than people gave it credit for. In certain areas, I think its better than the KSA. I see they sell for around $1500 used. At that price, you can't go wrong.
