I sold my duos 4months ago,they had the upgraded woofers, pre-amp and pwramp was cary triode single ended.could never get the upper mids and treble to blend musically with the lower bass.BASS was to slow in comparison to the upper registers. In talking with folks who have also sold theirs, one particular guy had his modified to no avail.I must say the speaker has great potential,but it needs improvment in this area.AS THE comment made above alot of them are starting to hit the used market.