Spica's TC 50 vs. Sound Dynamic RT 3's

The spicas are wonderful speakers but do need to be away from the rear wall to image best. IF you find a pair on Audiogon (or elsewhere) for a reasonable price I would get them and see how you like them ... worst case is that you lose the shipping since they're really easy to sell on. I have not heard (nor heard of) the RT3s so I cannot comment on relative performance. Hopefully another poster will fill in this information.
Since your main system is ESLs I find it hard to believe that you would not like the spicas if you have the room to keep them away from the rear wall by a couple of feet. SUre they're not ESLs but I think the design goals were similar ... imaging and midrange rather than bass and SPL.

I've had two pairs of TC-50's. The first was the original and the second has slightly better connectors, a cross brace, different felt configuration around soft dome tweeter and supposidly better power handling. The later model TC-50 was better. The TC-60 was completely different and I have never heard it. I modified my TC-50 with less internal "stuffing", internal wire replaced with cardas wire, new edison price connectors, removed the felt on the front. The sound of the TC-50 does have some coloration, kind of a signature midrange sound, excellent sense of space, imaging, phase coherency. Bass is very tuneful but unless you're in a small room bass can really lack (my current setup suffers from this). I find they sound best with cardas cables (they can sound too lean with the wrong cables). I don't have a tube amp but they did sound better on a tube amp I heard them on. They have a 4 ohm load so If you have a true class a amp like mine then their otherwise poor efficiency is alleviated somewhat. The spicas overall can really compete in terms of revealing detail, space, imaging even with real expensive pieces but have some harshness, coloration, damped bass compared to good proacs, charios, others.

IF you are used to the Quads, gotta go with the Spica's. Rt 3's are good, but the midrange on the Spica's just sneaks up on you letting you know how good it is. I would have to say the RT 3 has better low end, and actually more extended on top, but in the midrange and depth dept, and now that I think about and read a little more(I keep notes on everything I have ever listened to at home)in the focalazation and placement, Spica has it and really a lot of other speakers in the same price range. was one of those speakers that got it amazing right at the time.
Caveat though, Original drivers no longer made for the Spica, and the woofers had very tight tolerence's in the voice coil, so if you buy a pair used, make sure they are extremely well packed. Company in PA will rebuild the woofer cheap($40) but they are so busy it takes over 6 weeks to get them back.

I owned a pair of TC50's from 1990 through 1993. I bought them because I moved into a small apartment.

I enjoyed them and they served me well. They are not well extended in either direction but what is there is fine. They have a good upper bass, which can give you a feeling of what is below. I think it is generous to say you can get 60hz solidly from them but I never measured them

The midrange and sound stage is what made them enjoyable. Also, although they go south after 16,000 they have an Audax soft dome which is smooth. They won't play at head banging levels but can handle 90hz or so in the right room. They can tend to compress if driven too hard.

Finally, both drivers are hard wired with no protection. So, if you are not feeding them good clean power you can distroy the drivers. However, they were out sourced and easy to replace.

One more thing is that they do need power. They are not they most sensitive speaker. I would say at least 100 watts with current.

I am going to respectfully disagree with a couple of posters on the power dept.. They are not the most efficient speakers in the world, but also don't get the idea that they will play loud if they have plenty of juice. If its in your office, I doubt that it is much of a concern.Just treat them like you would your Quads and it will be fine. I thought they sounding great on Audio Research/Dynaco Stereo 70.