Pieter Kleinjahn has installed a Raspberry Pi, the HiFiBerry DAC, some buttons and a LCD display in one box.
The buttons can be used to control MPD. Distributions like Volumio and RuneAudio are based on MPD, therefore this could be interesting for many readers. Peter has provided the Python script that controls everything. You can download it here: mydisplay-20140409. Note that we provide this “as is” without any support. However, the code is clean and well-documented. Therefore it should be relatively easy to adapt it to your needs.
Our 
The LM317/LM337 is one of the most used circuits for low power audio applications. The performance is good. For most applications, these integrated circuits work really well. But sometimes you may want something better and more modern. There are two interesting ICs for audio applications:
Some phono enthusiasts prefer audio equipment with vacuum tubes. I’m also fascinated by these “old” equipment, but did not build a tube amplifier or preamplifier by myself. While the circuits usually are quiet simple, most of the performance of tube amplifiers come from the realisation. The grounding concept or the placement of transformers can make the difference between a great and a bad amplifier – even with exactly the same circuit.
