If it works then theres nothing to gain by changing. I am suprised you
do not get any interference. Most computers use switching supplies
which are well known to generate interference. They also lack much
filtering. IMHO most radio operators use linear supplies although there
are some good switchers available.

i run a samlex switching supply, and 25ah gel cell.
this powers my ft-847 and a bunch of other radios as needed.
the battery supplies the large currents, and the power supply just has to
have more output current than the idle drain of the radios. has been in
place now for probably six years. i pull the plug and cycle the battery
occasionally, but there's no real need.

while it is easier to make a bad switcher, linears can be just as noisy, if
designed badly.
switchers will have a small ripple component at 50-300khz, which isn't going
to cause you any problems in the audio path. their noise at higher
frequencies is usually just about zero. if not, time to get a different
switcher. i've used five different switchers that i can recall over the
years, and had no noise problems.

one note.. the charger connects directly to the battery, and the loads come
off the battery on separate leads. do not make the mistake of feeding the
charger in at the end of a cable with radios between it and the battery.

i use anderson powerpoles on all 12v gear, so everything in the car can just
be plugged into the bench, and vice-versa.