Speakers for First Watt SIT-1 amp

When I decided to change amps the SIT-1's (or new SIT-3) were on my short list. I, too, was hesitant to go with tube monoblocks as I have a small child and did not want to deal with the typical tube concerns (heat, short life, biasing, etc.). However, I got the chance to hear the Linear Tube Audio "Ultralinear" amp and was awestruck by the sound. Also, the amp is a unique design that promises extended tube life (10K hours+) and produce very little heat (much less that your class- A SIT-1s). You may not be interested in changing amps at this point but thought I would mention the LTA's, which are very special. I ran my Ultralinear with Daedalus speakers and the match is ideal. I've go new Daedalus Apollo's on order and am confident that this is going to be a great pairing. Next step is to add another Ultraliner and run them as monoblocks--should be fun.

Both Zu and Spatial make high efficiency high impedance speakers. I have a horn-loaded single driver speaker system as well and have heard a couple of mid-line Zu speakers and in both cases, almost regardless of the pairing amps - tube, SS, low or high watt, they all sound somewhat congested at higher volumes playing complex orchestral music content, As much as they excel in imaging while playing more intimate musical genres, they don't seem to be suited for rock and/or western orchestral classical music. Just my experience.

That's just the type of music I'm having issues with.  Has anyone heard single-driver speakers that don't sound congested with busy music?

Hello ggking,
You have created a very interesting thread and I will add that you have what is considered a unique and well regarded amplifier. You have received some very thoughtful posts from Audiogon members who are quite respected on this forum.

For all the positive attributes of a single driver speaker they have a few acknowledged shortcomings (as do any speaker niche). Playing complex or "busy" music and particularly at higher volumes is one of them. David_ten mentioned the Cube Nenuphar a new speaker from Poland. It was given a stellar review by Srajan Ebaen of 6 Moons. com. I find this very relevant given his extensive experience with single driver speakers (including the expensive Voxativ from Germany).The Nenuphar seems to have reached a new level of performance in this genre.

Another option is the Coherent Audio speaker (Toronto Canada). This is a 2 way design with a very simple crossover, 95db with an 8 ohm impedance load that is reportedly very flat. Based on owner word of mouth and professional reviewer show reports it sounds fabulous driven with low power amplifiers. I suspect it could be terrific with your S.I.T.-1 mono blocks.

BTW in the 6 Moons review Ebaen found the Cube Nenuphar to sound superb paired with the S.I,T.-1 and S.I,T.-3 amplifiers. He gave a slight preference to the S.I.T.-1.
Good luck ,
Charles

Id vote for a Voxativ ...perhaps supplemented with  a REL sub.  They have a FIT model now with a 5" driver ... perfect for mid size rooms.  $5700 with the AF2.6 driver. 
FYI, I owned a FirstWatt F7 and my Voxativ sounded lifeless with it.  I almost opted to try the SIT3 but the reviews were meh.