Purchased to try "fake" bi-amping in a home audiophile system, using an old (retired) Adcom GFA-555 for bass and the current amp, Parasound A21, for midrange and treble. Speakers at the €5.000 price point. The dBX was cheap but a few reviews appeared to suggest its usability with very good equipment.
First impression was full satisfaction and I really imagined audio quality had improved. After exactly two years a channel died (bad XLR connector soldering in the dBX quickly fixed by Thomann). During repair I reverted to Parasound only (now bi-wired). It took only seconds to realize audio quality had clearly improved. The refined TUBE preamp had lost many of its qualities being fed through the filter. The initial impression - lasting for two years - had been due to buyer bias: wishing to hear an improvement and never bothering with a more careful comparison.
Still a good unit for decent stereo systems with no deep 3D stage and or subtle articulation to lose in the first place.
Actually, the dBX is still in use, but now as a volume knob. The mid/treble amp is fed directly from the pre-amp's OUTPUT 1 and OUTPUT 2 goes to the filter controlling only the bass amp (filter set on the full +6 dB gain due to Adcom being unbalanced).
The dBX faultlessly handles the low bass 35-200 Hz and enables fine turning of the bass (using the gain knob) to better suit the room characteristics (room treated with bass traps but still needing a little decrease of bass). Bass control is also useful with audio sources where bass badly missing, such as the occasional vinyl LP with too long playing time (bass slightly decreased by the record cutter).
In conclusion: Good purchase although the filter ended up serving only as a primitive bass control. But it also makes the home system look boyishly cool.
