AVerMedia AVerTV Digi Volar X (A815)
It is perfectly supported in Linux, even the IR remote.
Very powerful at bad conditions.
[root@host] lsusb ... ID 07ca:a815 AVerMedia Technologies, Inc. ...
- MXL5003S as a tuner
Firstly, you need to copy the following firmware dvb-usb-af9015.fw in your /lib/firmware/ directory, or in the directory where your system will search for it.
It is supported in the latest v4l-dvb, so you have to download them first. Either getting  or using mercury See the How to Obtain, Build and Install V4L-DVB Device Drivers for all the details.
IR Remote Support
The latest developtment version of the driver gives support to the RM-FP remote control (thanks to Jose Alberto Reguero . But there are other remote control versions bundled with the device. RM-KS is one of those. Taking a look into the files that the CDROM driver installs, there are five files named: AP6RMFP.BIN, AP6RMHR.BIN, AP6RMHV.BIN, AP6RMJH.BIN, AP6RMKS.BIN, where the correct IR table to be used with each remote control (FP, HR, HV, JH, KS) is given.
UPDATE: Support for RM-KS remote is already included in this mercury repository 
Download and compile the drivers, and then use the option remote=5 when dvb-usb-af9015 module is loaded. In debian that is made adding (as root) a file called, for example, dvb, in the directory /etc/modprobe.d/ with the line
options dvb_usb_af9015 remote=5
There is a lot of information on how to make lirc work in Hauppauge_WinTV-NOVA-T-Stick#Remote_Control_Support
Due to some problems with the HID devices, in some machines the IR reception is buggy  (i.e. irw gets correctly first button pressed, but then gets stuck in a weird loop where the button seems pressed all the time) To solve this, you can create the file /etc/modprobe.d/usbhid containing:
options usbhid quirks=0x07ca:0xa815:0x04
and then execute
$ sudo update-initramfs -u
and reboot. The problem should be solved that way.
Not stable in 24h/7 use. After a few days recordings have a size of 0 bytes. Only known solution: Unplug the device for 10s and do a reboot.
Test your drivers
Once compiled you can try this: Testing_your_DVB_device. Kaffeine seems the easiest/fastest way to check if it works.
Compared Avermedia DVB-T Volar X vs. Club 3D ZAP250m (one of the best devices in 2006) at bad conditions at the same PC and the same antenna:
Signal strength at 578000000 Hz: 40333 vs. 15420 Signal strength at 690000000 Hz: 28143 vs. 19275
--Pipeta 17:19, 25 January 2009 (CET)