JM Lab Utopia Sub

Is there any added benefit to match the Utopia sub to the Utopia lines of speakers such as Mini Utopia or Mezzo Utopia? Is it worth the money to add the sub for a few low Hz's (for music) and any one care to give honest feedback on the Utopia sub (performance wise as compare to Velodyne or M&K)? Thanks.
I have recently traded in Aerial 7B's with two Vandersteen 2W subs. While the subs filled in the lower regions, their greatest benefit was that it permitted more power to go to the 7B's and, boy, did they open up! Much more dynamic and lively. I considered the MIni's with the 2w's, but the Mezzos are in a different league...even with the subs, the Mini's aren't as complete a speaker system as the Mezzo's...the Mezzos are special, particularly when mated with a great amp.
I owe JMLab Mini Utopia partnered with YBA amplification and cd player.
I too want to put a sub to filll the frequencies below 45-50Hz I am thinking the REl Strata III has anyone any experience?
I also would like to ask your opinion on different connections (through the second output of my preamp or in parallel to the amplifier speaker terminals.

There is also another thing that puzzles me if one is to use a sub what happens to the frequencies that both the main speakers and the sub produce.Is there any overlapping?since there is no active crossover in the chain??
I would apreciate your thoughts and insight
Robathome - Could you please suggest a few great amps for the Utopia speakers? Tube or solid state?

Mahler - I believe going low level from the pre-amp to the low level input of the sub would be better than parallel speaker cables between the amp and the sub.(IMHO)
May be other experts can provide more information for you. Since you owe the Mini, why would not you consider the Utopia sub? Is the Rel better?
I will try JMLab sub also but is more convenient to see how it matches with a sub first and then go for the Utopia sub
Any comments on the active crossover and the possible overlaping frequencies??
I have no experience with the active crossover but I believe it blend in the frequencies between the sub and the full range speaker a little better. In regards to the frequencies overlaping between the sub and the full range speaker when you run in parallel is not an issue if you take the time to tune in the sub correctly. Try to adjust the sub cross over first then adjust the volume control and repeat until you feel right. If you have the Mini Utopia, you can start the sub at 60hz and slowly go down to about 40hz (until the sub and the Mini blend in). I believe the Mini goes down to 50hz so play around within that range. I hope this help. If we have better suggestion, lets hear it.