Cowman,
You are absolutely correct on all the points you raised. My Cayin SET m'blocs using 845 op tubes are rated at 28wpc and they are very happily matched to the Spica TC60s which I bought used at low cost. I don't know the efficiency of the Spicas; unfortunately the manufacturer has gone away, so such information are not available for this forum discussion. I think the sensibility might be around 87/88 dB/w/m. Spica owners reading this may want to join in with the correct information. The 845s at 28w definitely open up a lot of good speaker options, the likes of TC60 in the used market. Sorry am not able to advise on the da Capo, but Cowman is right about exercising care matching SETs with higher relative efficiency speakers.
Don't give up!
You are absolutely correct on all the points you raised. My Cayin SET m'blocs using 845 op tubes are rated at 28wpc and they are very happily matched to the Spica TC60s which I bought used at low cost. I don't know the efficiency of the Spicas; unfortunately the manufacturer has gone away, so such information are not available for this forum discussion. I think the sensibility might be around 87/88 dB/w/m. Spica owners reading this may want to join in with the correct information. The 845s at 28w definitely open up a lot of good speaker options, the likes of TC60 in the used market. Sorry am not able to advise on the da Capo, but Cowman is right about exercising care matching SETs with higher relative efficiency speakers.
Don't give up!