My Trace Elliot pre-amp gives me all the EQ control and flexibility I need.  I tend to use a brighter sound to try to get that Entwistle tone, the Trace is helpful in achieving that.  I've never A/B'ed it with an Alembic pre-amp, but I would imagine the difference wouldn't be compelling enough to make me switch.  Also, like John above, I prefer a tube pre-amp.  My power output is solid state but my Trace has a tube pre that is fairly noticable in terms of adding warmth.