It surely can't be a lack of volume or headroom. Like Conan, I find my LH500 can go monstrously loud even into an 8 Ohm load, and I'd have thought a 4x10 with the volume at 7 in your living room would be...erm...painful !
It is though, as has been said, a very clean amp. I use mine with a Barefaced Compact, and I have to say that the combination took some getting used to at first...not least because it's very revealing and not at all sympathetic to poor playing. Made me realise how lazy & sloppy my technique was at times
The EQ can seem a bit odd at first too. A "flat" EQ is something like: bass & treble wound way back, with the mid cranked way up. But they seem to be kind of interactive as well - drop the mids, say, and it seems to change what the other controls do somewhat.
I don't know your cab, or what your sound/tonal goals are, but I'd take some time to experiment with the EQ. There's also the fact that it might just sound different to what you're used to, and once you've "forgotten" your old sound and become more familiar with the new it may completely change your view. Or it may just not be for you.
re: the volume control...yes! Some amps give the impression of being loud by putting all the control in the first half of the travel, and not really changing much beyond that. The LH seems the other way around, which I really like. Up to about 6 on mine, the change in volume isn't that dramatic - which I find good as it gives better control at lower volume.
My gear was used as the "house rig" at a 50th birthday bash last weekend - lots of musicians there, most of who had all played with each other (ooh-err!) in various combinations over the years. Lots of swapping band personel over the course of the night, and I got to hear some other bassists using my setup, which I haven't done since I got the Compact.
Have to say, it sounded absolutely monster