I got mine from Etronics. The first was defective (bad motor or something, the tape hesitated on recording or playback), but the second is perfect.
Etronics is a good place to deal with if you know exactly what you want, and they have excellent prices. They're also a legitimate Sony dealer. (I found one or two places that seemed lower in price, but they were out of stock, unresponsive to questions, or charged more for shipping.) The website is a bit slow to load, but it accurately reflects stock. They ship the same or next day, via UPS, and pack things very, very well. Good return policy on the defective item. But like most mass-market discounters, if you open it, and don't like it, you may have trouble with returning it unless it is defective -- find the policy and read it very carefully. I've bought four things from them, and recommend them if you are ready to buy and will keep something you really want.
On my desktop, I'm using the Radio Shack filtered and regulated 3-12 V 800 mA adapter, with the M plug, tip negative (same as the D-25S). The Sony adapter is no longer available -- it was 6V and 750 mA (neither filtered nor regulated). I also got the 6V 1000 mA regulated international adapter (the tiny little thing).
I bought 1800 mA Nexcell AA batteries and an Altek fast charger from Thomas Distributing. The WM-D6C takes four AAs. I didn't time the batteries' life between charges, but they last through about 4 90-minute tapes; so figure the life is something like 3-4 hours (with the display LEDs turned off except to monitor battery charge). They work very well. Consistent power output until they're empty. Then they stop. I will time the battery life if anyone is interested, but they seemed to last at least as long as a set of Duracell Alkalines. But the variables with the batteries are whether or not I'm using the lineout or the amplifier, whether the LEDs are on or off for recording or playback (or just switched off), the length of the tape in the unit, and the cans they're driving via the amp.
It sounds wonderful -- and I can't hear *any* Dolby C mistracking with TDK Metal tapes (MA-90, MA-110, and antique & rare MAR-90 reference cassettes) recorded in my recently-tweaked Nakamichi. Some very slight differences in high frequency and true low frequency response, but that's absolutely normal for tapes recorded on another unit. It is harder to record on this than on a regular unit, because the level indicators are fewer than on my Nakamichi. Tapes recorded on this unit directly from my D-25S CD player sound almost identical to the original.
Portable? Well, it's pretty large! But it is built out of metal, and the workmanship and materials are top-notch. It's a great thing to use on your desk. Plenty of power, too. If you have to carry it, the cover for the unit, and the strap, are well-built! I'm waiting for a Pelican Micro case to keep it in, and right now I keep it in a Polartec drawstring bag that fits exactly (luck).
It was the concert-tapers' weapon of choice until DAT came out. And yes, many live concert albums were recorded on this unit. If you went to any Grateful Dead concerts, this was the ONLY thing you saw tapers using (legally).
The MDR-51L phones they pack with it were interesting. They're small open supraural cans, very comfortable, and made very well (lots of metal and quality plastic and rubber). The Sony Parts price is $80, but the real price for these when they were sold alone was probably something like $35. The midrange is OK, the bass is surprisingly good but mostly mid-bass, but the highs are really irritating (break-in made no appreciable difference). If the highs were better, they'd be a nice thing to carry around. I packed 'em away, but will try them again with my Corda HA-1 just to see if there are any surprises there.
