I can't comment on the REL line, but I have found the addition of a sub, (I use an M&K MX 700,) to be the finishing touch to sonic bliss. The M&K is controllable to adjust for your room and monitor's abilities, and that feature should factor into the REL equation, IMHO.
You should also go to the Harbeth Smartgroups, (access through the Harbeth website,) and post this question there as well. (Maybe you know this, I think I recognize your moniker from days past.)
Good luck,
Charlie
You should also go to the Harbeth Smartgroups, (access through the Harbeth website,) and post this question there as well. (Maybe you know this, I think I recognize your moniker from days past.)
Good luck,
Charlie