Yes, just done it.
Its no better
As I thought, the b-sting aerials on these cars are not good enough for DAB in the UK as we are not transmitting a strong enough signal. Best reception I have had was with the Original Pioneer AN-DAB1. Unfortunately it was just to intrusive on the screen so I'm not going back to it.
This splitter will do for now but I am going to look into an alternative Aerial to replace the OE one with completely. Its terrible quality and I need decent reception across all frequencies not just the ones transmitting with the most power (R1) so a complete swap to an alternative unit with dedicated DAB/AM/FM & GPS arrays is needed.
Jaba, the big problem is that digital broadcasting is at the moment still limited (look how it looks like in Germany https://version2eureka.files.wordpre...pg?w=342&h=337
) until they kill the analog TV channels and free up some RF space. In the city center reception is acceptable to good. As long as you go towards the suburban, starts dropping significantly. I manage to get literally to border of Berlin (Schönefeld Airport) and then loose the signal.
regarding mod of the aerial per se, I was having idea of changing AR's OEM with Volvo's GPS/GSM/FM antenna. I even bought one on eBay. Unfortunately, that antenna is only GSM/GPS, no FM. I like this compact antennas, since they allowed me to mount something on roof (kayak, roof box, aerodynamical spoiler when towing my caravan).
that triggered me to start thinking on how it was done on 156: rear windscreen heater was also the aerial. but do not know how the connection is done and does it requires some adapter to split power for heater and signal.
alternative would be VW
mini-me aerials like this one
or, if you not minding having big stick, this
older ones. check both links since giving some nice technical data that might be usefull.