Actually he is not a loony and you are basically 100% incorrect. Just about all the common PCI TV capture chipsets have onboard audio A/D converters for audio streaming onto the PCI bus. They also have I2C controlled digital audio pass through for digital audio sources, the most common being NICAM stereo decoder ICs (stereo analog TV audio in the UK, France, Scandinavia and a lot of central Europe is broadcast using a multichannel, 32kHz digitally encoding system transmitted in the side band along with standard AM mono audio). These days there are only really two big players in the TV chipset market - Connexant and Philips.
Connexant have two common PCI TV capture ICs - the Fusion 87x and CX288x familys. The Fusion 878 has a single channel A/D converter that captures 16bit LE signed audio at 32-448kHz - most boards have a line from the Tuner or audio switching IC to the A/D converter. The CX288x family have a more sophisticated audio processor that can do AM and FM-FM analog inputs at 32kHz and 44.1kHz onto the PCI bus. It also has a NICAM digital stereo decoder onboard. Just about all of Hauppauge's analog capture cards without an MPEG decoder are BT878 or CX288x based, as are most of Pinnacles older cards and most LeadTek cards. The BT878 has been by far the most common capture IC on the market over the last 4 years or so, although Connexant are trying to phase it out in favour of the CX288x. Even so the mainland Chinese OEMs continue to churn out BT878 based cards by the thousands under literally hundreds of different brandnames. The CX288x is also very common found on "Blackbird" reference design cards with the companion cx23416 MPEG2 encoder chip - most of the new Hauppauge WinTV PVR cards are based on the "Blackbird" referece design.
Philips have two major families of PCI capture IC's - the SAA713x and the SAA7146. The latter is usually only seen on MPEG capture cards (like the Philips "Empress" reference design) and a lot of the first generation DVB-S reciever cards (which were almost all based on either Siemens or Technotrend reference designs). The SAA713x is becoming very common - it has an AM and FM-FM decoder and onboard A/D convertor for audio that can capture at 32kHz, 44.1kHz and 48kHz. It also has a NICAM digital stereo audio reciever. Most of Pinnacle's newer analog and analog-DVB hybrid cards use the SAA7134, Asus's TV-FM cards use either the SAA7133 or SAA7135, as do a lot of the Compro cards. There are also a couple of Chinese mainland OEMs offering samples of SAA7133 cards based on slightly modified copies of Philips reference design, so they should become even more common in the near future.
All of the abovementioned chipsets also show up in a lot of Digital TV receiver cards, although they are usually only being used as a PCI bridge and I2C bus controller in those applications - an external digital TV dmux IC takes the signal from the tuner, demuxes the stream and outputs the MPEG-TS to the TV chip for PCI bus master transfers. On BT878 and SA7146 based cards the MPEG-TS stream goes over the digital audio input line, the CX288x and SAA713x chips have dedicated MPEG stream input ports for external MPEG sources like analog encoder chips and digital TV demux chips. Even though many of these terrestrial digital TV cards are theoretically capable of analog TV capture, almost all of them cannot because the Tuner is only connected to the digital tv demux chip and not the TV capture chip itself. The Pinnacle Mediacentre 300i is one of the few that can do both analog and digital reception on the same card.
I personally own a couple of Hauppauge Win-TV PCI's (BT878) and a Pinnacle Medicenter 300i (SAA7134 + Zarlink MT352 DVB-T demod) in home theatre/PVR PCs and I record TV audio directly off the card without a pass through cable and without using the PCs own sound card to capture audio. I can simultaneously timeshift one program while recording another or record two programs on different channels simultaneously without the need to use the A/D converter on the PC sound card - it also means you can record without having to mute the sound card output volume if you don't want to hear what you are recording.
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