I have the alneo XA-C210, which I bought in May. I know Audiocubes was selling it in May, then they weren't for a while, and now they are again. I got mine from Eisanmall.com for less than Audiocubes' asking price. Eisanmall also carries the XA-HD500, and they have free EMS shipping for all orders. The XA-C210 has been available in Japan since about January or February of 2007. The XA-HD500 was released in 2005 if I'm not mistaken.
I'll try to provide information that will be useful. The XA-C210 does have the option for gapless playback. The manual says you need Windows Media Player 10, but I've been able to sync with Windows Media Player 9. Honestly though, you don't need the CD software that comes with the player if you don't want to. If you do, it can install in either Japanese or English. Additionally, you can just drag and drop your songs into the "Music" folder, make subfolders and drop files in those, etc. The player will update its database and arrange them all in the menu.
You can listen by artist, genre, track name, file name, release year, new tracks within the last day, 2 days, or 1 week. The instant playlist generator has the categories: recommended, top 30, recently played, morning favorite, and never played. You can also "bookmark" songs to add to your custom playlist, and "reserve" songs on a temporary playlist for later listening. Of course, there is random play also. The player can also display album art for your music, and you can delete files without being hooked up to a PC.
The XA-C210 has the K2 technology option just like the XA-HD500, but not the CC converter. I really don't know how much difference that would make, but I was looking at JVC's product sheet, and it seems the audio capabilities of both are pretty much the same.
http://www.jvc-victor.co.jp/download...summer_v01.pdf
It's also worth mentioning the C series uses a color screen while the XA-HD500 uses a monochrome one.
In addition to the K2 converter, other sound options for the C series alneo players include Digital AHB (bass boost), 4 types of surround sound configurations (energy, crystal, heartful, and subway), up to 4 custom equalizer settings, HP Output (I'm assuming that stands for headphone output) of normal or high, R/L balance control, the option for stereo or mono, "train mode," and MNR (noise reduction).
The FM radio tuner for the XA-C210 is set for Japan FM radio frequencies, so it only picks up 76 to 90 MHz. Ironically, I can pick up NBC on it.
On JVC's website for the C series alneo players, they have Wall Art Changer software so you can change the background image in the player to one of their preset options, I believe. I haven't used this myself.
http://www.jvc-victor.co.jp/alneo/wallart/index.html
New firmware for the C series was also released on July 12. I don't know what the updates are, as my Japanese isn't that good.
The XA-C210 does not include the AC adapter in the box, so if you want one, the product number is AA-R511.
The player connects to your PC and can charge via a mini-USB cable, which is included in the box. Transfer speeds seem pretty fast to me. While the player is connected to your PC, you can stream the files for listening through the PC (i.e. via Windows Media Player), but listening from the headphone jack is disabled.
The buttons Function 1 and 2 are programmable and you can assign virtually any function the player has to them. You can program 4 of them (single press of the button vs holding the button down x 2 = 4), and I find this quite useful actually.
The LCD screen is close to the size of a Nano screen, so screen protectors built for Nano will fit on the alneo C series. I use one myself.
The player features line in recording, but also has built in mics so you can record without plugging one in. It can also record from the radio.
I don't use the picture viewer too much.
The player is able to read unicode, and can display file names in 27 languages, if I'm not mistaken. Menu display options are Japanese and English, with Japanese being the default, but it's not hard to change.
With the internal clock, you can also set an alarm or a preset playing time before the player shuts off, which is nice if you plan to go to sleep listening to music.
I use the Etymotic ER-6i with my XA-C210. There is a very minimal hiss, but really most of the time I don't notice it, and it's not a bother for me. I really love this player and the sound quality, but as a disclaimer, this was my first portable DAP, and ER-6i are the best headphones I have.
If you have more questions, I'll try to answer them.
