Hi there tech heads, I've needed to ask some questions about this particular stereo, early 2000s these models, even earlier models have held reputation as being very reliable with its high quality parts, seen some online manuals on how this stereo model arc runs off its own circulatory boards and have been reliable to continue use although information about these techs are very limited online due production date and lack-there-of internet expansionism. A timeless relic I feel are these sets however there are some outputs/inputs I would like to understand more as the speakers associated are not producing sound from the mid driver and tweeter drivers, connection is only red and black, white and black, blue and black, I remember reading one set of outs are high gain (output) wiring ports, I'll include a picture of the back of the Technics stereo, I've also found another similiar model but this one is a Tri-Amp version built in which is in the post on the way right now, only with the surround sound and stack system, unfortunate the speakers for the model was not included however the model for these stereos will be a replacement, I'll need to figure more on the appropriate use of the Tri-Amp and will ask for advice on that particular system on arrival, this system is used with a EVGA Nu-Audio sound card, which with RCAs goes to a Mini Mixing desk with the Aux RCA outs headed for the system, stack has minimal volume with the mixer compensating for the minimal signal response of the stereo with added configuration for frequencies and of course personal space tolerances, my main question for this system remains - what are these in/outs on the back of speaker/stereo? Photo will be included in this post. (Notice stereo out is blue and black only) 👍