I also had a Quickie "revelation" - sound was good, but obviously had its limits, through headphones via the Specos. Feeling as though I never truly "drive" the driver sections of the triodes on the S.E.X. amp (esp. feeding it with the Seduction, which only has 40dB gain with the C4S boards), I placed it between. Sound was okay, but I noticed something funny about the bass notes and soundstage - it seemed as though something was dragging down the load, making for weak bass and anemic transients. Then I remembered that the Specos were still in the circuit. I clipped the leads as I listened, and the transformation was amazing! The soundstage was the same as the stock S.E.X. (that is, open, 3-dimensional, and airy), but the bass and "slam" of the notes was much better and more dynamic with the extra gain the Quickie provides. If I had let the thing sit on my computer desk and live its life as a headphone amp, I would have done it a disservice! After a re-finishing of the wooden base to match my other Bottlehead gear on my "main" system, it will take its rightful place in my rig.
In short, I encourage everyone not to judge the Quickie just through use as a headphone amp (with $3 OPT's, no less). Plus, make sure to take the Speco primaries out of the circuit if using it as a pre-amp, otherwise, it's like driving a Ferrari with the parking brake on.
