How to use stand alone pre-amp with HT?

I've seen it recommended that those of us using pre-amp processors can improve our music performance by using a stand alone (better) pre-amp.

I am currently using a Arcam AVP-700 which is highly regarded for it's two channel music performance. It does have a two channel by-pass mode which I use, but I think the volume, etc. is still digitally controlled. I'm not sure if this is good or bad.

Anyhow, I'm stuck with using one system for HT and music and I'm trying to get the best of both worlds. I'm totally satisfied at this point with my HT, but am not convinced I can't do better for music.

The rest of my system is a Naim CD5i, Outlaw model-755 five channel amp, Energy Veritas speakers. Still experimenting with various IC's, use Alph Core Goertz MI-2 speaker cables.

I'm also thinking of upgrading my front two channels with a better amp, but some have suggested a better pre-amp would make more of a difference.

I would like to know how an outboard pre-amp can be used with my existing system, and if you think this would be a better upgrade or the amp. If memory serves, I'll have to use a tape loop, but this still routes the signal through my Arcam, so where how would there be an advantage.

Please help. Thanks.