Hi astralpen :-)
If not for the fact that your amplifier is tube while mine is SS (it could very well be that a tube amp reacts to the AirSine in a different manner) I might agree with you (in effect), since I also find the AirSine to provide more profoundly improved performance when placed on my preamplifier (jawdropper) vs. placed on my power amplifier (not so jaw-dropping, but sooo clean-sounding and certainly without any sonic drawback, IME). So, it would not be much of a surprise to learn that many folks would prefer to use the AirSine for source components rather than power amplification (if the low-level signal nature of preamplification counts as being related in function to that of a line-level source component).
However, when placed on my power amplifier, the AirSine's excellent transparency (lack of pronounced sonic signature) is of such great importance that I’ve not pursued another power cord option for that particular application -- the AirSine that's placed on my power amplifier seems to provide excellent synergy with the AirSine that's placed on my preamplifier (if it ain’t broke, don’t fix it...). Perhaps a cumulative effect may be involved when AirSine power cords are placed on both preamplification and power amplification (as well as source components for that matter) within particular systems.
One thing I that find to be very important is to mate a particular AirSine's AC connector termination option with a complementary-synergistic AC outlet. Both of my AirSine’s are terminated with gold Wattgate 330i Audio Grade AC plugs and gold Wattgate 350i Audio Grade IEC connectors; when mated with silver Wattgate 381 Ag Audio Grade AC outlets, the gold/silver combo seems to provide a similar synergistic phenomenon to that of “the best of both worlds” gold Oyaide 079 AC connector and palladium Oyaide SWO-XXX AC outlet pairing (tonal bloom/warm sonic signature meets lean/analytical sonic signature = balanced tonality and outstanding soundstage presentation). YMMV
Cheers, Duster
