^^^^
Legally you MUST have an operational rear red fog light and that can easily continue to function as it does now.
Technically if you are to follow European rules (very strongly advised if you drive in Europe) your DRL's should be installed so they automatically switch on with ignition and off when switching to any other light. I haven't checked if Audi's do this but I've got a big latest 09 Audi to play with soon.
That is categorically NOT what the EU regs state. DRLs can STILL be used with side lamps, dipped headlamps or main beams - which is exactly how Audi, part of the worlds third largest car manufacturing group have been doing for some time now!
Fogs are a signal light and DRL's (proper ones, not Volvo dipped headlights) are a passive light. The two are independent in all respects.
Front fog lamps are NOT classed as 'signal lights' - ONLY indicators are classed as 'signal lights'!
Secondly, DRLs, be they LEDs or tungsten filament lights (like on Volvos) are NOT classed as different - and are IDENTICAL in their function.!!!!
The UK authorities have discussed that they may allow fogs to be used for a transition period when DRL's become compulsory on all new cars in 2010(?).
Where the heck did that bollox come from? Fog lamps will NEVER be allowed to be used in anything other than fog - end of!
As fogs are signal lights and so can obviously dazzle, this makes a mockery of the purpose of DRL's, but why am I not surprised!?
Fog lamps are NOT signal lamps, and when front fog lamps are correctly aligned - they do NOT dazzle. They actually cause less dazzle than a correctly aligned dipped headlamp - which is exactly why a correctly adjusted fog lamp will perform better in fog compared to normal dipped headlamps.
It is only your very wrong information, or wrong interpretation which is making a mockery of this issue - the laws are crystal clear!
If you find someone to install the S6 DRL's, they should know how to wire and switch it. But will they know the Euro rules? My MOT tester didn't until I told him.
Sorry, Robin, but you have interpreted your so-called 'Euro rules' with a major error! DRLs do NOT have to be switched off when headlamps are switched on! Or do you think you know better than Audi AG?
It sounds as if you intend to keep the oem fogs and simply (well, it's not simple unfortunately) add the DRL's independently.
Hurdy has aftermarket headlights which incorporate LED strip DRL's, but you can't install those if you have and want to keep Xenons. It's all in this thread.
Stealth does NOT have Xenons, so Hurdys lights would be ideal. But for those with Xenons, then just use the Xenon dip as a DRL!