Teclast C260 is a rockchip device... sound is average... video ranges from good to very good, considering it's resolution of 320x240 and 262k colors.
What is good with Teclast is there are frequent upgrades of firmware, adding new functionalities, nowadays is support more audio format than other devices: WAV, WMA (all range + lossless), APE, FLAC, no support for OGG.
video formats: AVI (xvid), FLV (native)
Teclast have also a nice fansite (www.teclasters.com)
You can buy not only a Teclast machine, but also Teclast C260 compatibles to enjoy the firmware.
Anyway, rockchip is still a raw OS, with no MTP support yet.