DC source noise rejection filter for DAC/headphone amps

When I first purchased my DAC 4 years ago, it came with a 15V DC linear power supply. As you know, linear power supplies are very heavy and bulky, especially when their power rating is high. On the contrary, switching power supplies are light and small. But there are always pros and cons. Despite all the excellence over the linear counterparts, switching power supplies usually have high output ripple and noise. The output noise is quite intrinsic due to its mode of operation and very hard to avoid. Therefore, at least for applications where the noise is a big concern, linear PS is a good choice.

If for some reason there is no other choice but using a switching power supply, a hybrid type power supply can be used. For example, let's say that we want to get 15V DC source. Then we start with a 18V switching PS. Because the output may have a lot of ripple, we can trim it out with a linear regulator of 15V output. There are bunch of linear regulators out there with superior ripple rejection characteristics, so we have very high degrees of freedom in the part selection.

The followings are my design:

Parts:
LM1084 x 1
capacitors
  10u x 2
  100u x 1
resisters
  150 x 1
  5k x 1 (variable)
panel mound DC jack x 1
5.5/2.1mm male DC connector x 1
heat sink x 1
volume knob x 1

The most challenging part? Well, it was so tricky to pack all the part within a tiny case.