i was using the spec-1 and spec-2 with 4 HPM-150 in a 50 square meters room as source i have a cd player the CEC belt-driven from the 90´s but still sold today and a PLC-590 with a AT tonearm and a 70´s AT cartridge mc type, now i have changed to two monoblocks M6 and a C3 controll amplifier with a all original P3 turntable and a cd player from magnat released in 2016 ,i think tube pre-amplified , i prefer the sound of the exclusive system ,i almost forget, i´m using two twin 2401 speakers also from exclusive pioneer all was recentelly restored to original specifications also have in use a studer open reel deck four track recording in stereo and before i was using a 77 B series from revox, both this systems by pioneer sound perfect, today is very expensive and maybe not that good in sound quality to match this systems and i have more but this was what is refered in the video, i colect hi-fi components also this year had conected a C1 yamaha control amplifier with a B1 amplifier with some JBL studio monitors similar the 2401 twin speakers or built by the same engenier that were in my home studio built in 1970 by my father and improved as it was possible to do so, the spec-4 i never heard one but i think it´s the same sound of the spec-2 ,one can´t find better ,only equal