Have tried them and they seem to help in most transistor applications but damage tube sound. Current is everything in audio. These seem simply to increase current to better drive the next amplification stage of the audio chain. Sadly, current seems to have been ignored by most manufacturers. Better to search out components that have a higher current output.
Harmonic Recovery "Boxes"
Clement Perry has new review of another "black Box" harmonic recovery device. Are these the panacea some claim or just another device that filters or colors sound, what are members thoughts on these devices? Sam