There are two.
1) Acoustat 1+1 & RTR ESR 15 disassembled, and arranged in a line source next to the Acoustat panels, with the Acoustat HF Transformer removed, which allows you to use natural roll off of Acoustats crossing over to RTRs. It also increases efficiency,and detail, by removing haze caused by HF transformer to equalize HF response. Combination give you coherence, and dynamics. Easily driven with HQ 30 watt triode wired tube amp. Best with Subwoofer, as the Sunlights but imaging, detail, and dynamics are superb, and tall line source does wonders for helping wall and ceiling reflections. They were the best I have heard, until:
2) Sunlight 308s. Simply amazing speakers. I am driving with a 2.5 watt 6a3 Triode single ended amp. Doc Gizmo got it right in his "Triode Guild" write up of these speakers. Acquired from Johnk who probably regrets letting them go. All of the positive aspects of the Tannoy's that people rave about on the Tannoy sites, but with no veiling,or the power requirements to drive them, as well as much more detail, and great imaging. HF is limited to 17k, so system also included a Fostex t90aex tweeter horn tweeter to 40k, and a pair of Audio Pro B2-50s for the bottom end.
Both speaker systems were/are the best I have heard, and I would be had pressed to choose between them, assuming I could recreate the Acoutat/RTR system. The advantage to the Sunlights is that a very high quality low powered tube amp is not as expensive to build as a very high quality high powered tube amp, but they are heavy, and bulky to move around. the problems with the Acoutat/RTRs are that they are electorstatic, with high voltages, and the power supply of the RTRs can be cranky, to say the least.
