Steve,
I've had my WA2/LCD-2 combo for a little over a month. One of the reasons I chose the WA2 was for the preamp functionality. My experience with it has shown me that it works quite well as a preamp into powered speakers with one caveat. The caveat is this:
If you happen to have a pair of LCD-2s headphones connected at the same time you will notice that the volume level to your speakers is almost halved! Remove the LCD-2s while music is playing and the volume magically increases. Plug them back in and the volume drops. Now plug in a pair of 600 ohm DT-990s phones and the volume never changes while using the WA2 as a preamp. Now, I appreciate that you would not normally be listening to speakers and headphones at the same time, but I tend to leave my headphones attached to the WA2 and as a new owner, at the time, having 1st read the WA2 manual, I wasn't expecting this behavior.
At first I wasn't sure if the WA2 was broken or not, and the WA2 owner's manual is very light on useful information about using the WA2 in general and as a preamp in particular: especially any negative interactions you should watch out for.
I emailed Jack Wu about the problem and he wrote back that it was due to an impedance imbalance when the LCD-2s (50ohm) are connected at the same time the WA2 is connected to an amp or powered speakers. Lesson learned: don't keep low impedance headphones attached to the WA2 while using it as a preamp.
I hope this little bit of info helps.
