The built-in radio is actually not too bad: RDS, DC, and a reasonable sound. Also it has a built-in timer which keeps it on for a while after switching off the engine, before it automatically shuts down. This is quite convenient. But a major drawback is the volume regulation by key only. It takes me forever to set the proper volume. Also, after switching it on, it is at a low volume level of 20 - I have then to bring it up to 40 to have a decent sound level. And the two up/down keys are a bit fiddly to handle while driving, with slow reaction. I prefer a rotating wheel, which nowadays almost all radios have. So I was looking for a replacement, and found the Sony CDX DAB700U. This is a DAB radio, which is absolutely appropriate for a car: no hiss anymore, clear sound, and all those fine sound details which are a bit lost in the digital compression are not noticeable because of the general car noise anyway. A great feature set, and not too expensive: £ 115 + shipping.
I had no trouble getting the old radio out. Two of these special prongs were needed for pulling it out, which I already had. Installation of the new radio was also easy, although at the DIN opening in the dashboard there were two little plastic nudges which I had to remove, as they were in the way when I slid the metal frame into the opening. I also had to drill a hole into the top cover of the dashboard, for the additional digital antenna. DAB reception requires a separate antenna, as this is in a different frequency. I had to make the hole quite large, to fit the connector through. The cable itself is not very thick.
One small issue after the radio was wired up: Sony and Fiat seem to have different opinions on proper coloring the cables. Sony has the convention to use red for the 12V+ from the ignition and yellow for the constant 12V+. Fiat has it the other way round. So when directly connecting the out-of-the-box wire harness, the radio switched off completely after the ignition was turned off, and when switching the ignition on again, all the settings had been lost, indicating that the main power had been disconnected. This could be corrected by swapping the red and yellow connectors, as also shown in the instruction sheet. Fortunately, Sony had been very thoughtful in having separate plugs and sockets on these, so one could just unplug and replug these in the proper positions.
A better option would have been to guide the DAB antenna cable somewhere behind the dashboard, but I did not want to begin messing with opening the dashboard.
The antenna is to be attached to the front window, with self-adhesive surfaces. I did try to find in the manual some information about in which direction the antenna needs to be mounted (horizontally or vertically), but was unable to find the instructions. So I thought, since it is a dipole, I might put it up horizontally on the top edge of the window. This turned out to be a mistake, as I realised shortly later, when I found the small picture of the antenna mounting instructions on the foldable "first steps" flyer that was part of the instruction set. The antenna should have been mounted ad the side of the window, vertically. Now, that it is already attached, it is virtually impossible to remove it without damaging it. Well, I did drive with the radio on, and the reception with that wrongly mounted antenna was ok. In tunnels it was reduced to 0, but that was to be expected - is the same with the regular FM. So at the moment I will keep this antenna as it is, but I did already order a replacement antenna to be mounted in the proper position. Then I will compare which one is better, and will then be able to tell if this makes indeed a difference.
One criterion for choosing this radio was actually the fact that it had a remote control and therefore could be used as the main entertainment center for the campervan. The only thing I would have to do is to bring the power from the leisure battery to the radio, instead of from the vehicle battery. I could simply put a manual switch in, but I am thinking of putting an 8-pin relay in which would re-route the two power inputs to the leisure battery, once a voltage from that battery would be provided.