These items are sold as is and preferably together. Sherwood and Onkyo tx-sr503 are 2 wonderful and fully functional 5.1 channel home theater receivers NHT ma-1a- subwoofer amplifier works really well but the input needs some very light soldering. Pioneer sr-720 great vintage stereo amplifier. This model is missing the volume knob but the Potentiometer works well. The only other issue is that the right channel distorts at slightly above normal volumes. Harmon Kardon hk -3300 stereo amplifier same issues as with the pioneer, I cannot however remember which channel the distortion happens. It is also more present on this amp. Again all of these are sold as is. I could fix most of them myself but don’t have the time.