Thanks, I probably will try again next week with that. I was just a bit worried by this PCM VBR FLAC thing that Tidal shows. Yet the menu says it is playing FLAC
FLAC is 'variable bit rate', and produces PCM. So I think you're OK.
PCM is constant bit rate, for example 44100 samples of 16 bits per second, two channels, gives 44100 * 16 * 2 bits per second, 1411200 bps, which is a lot when most of them are zero. FLAC does a loss less compression, so it will turn proper silence into a very small number of bits, and not do a very good job at all with perfect noise. So the resultant bit rate varies from moment to moment, but with 16 bit music averages about half the raw PCM rate.
Some of Jim Audiomisc's threads relate to how to do better than this at no subjective cost, prompted I think by the mumbo-jumbo surrounding MQA.
Your Pi is running a Linux distribution, which is a complete general purpose operating system you may have heard of, the suppliers you have chosen have stripped out a lot of the irrelevant clutter, installed the player and library components of their choice and skinned it with a web based interface to make it easy and relatively friendly. You can however connect to the underlying OS and work with it directly, SSH is the standard protocol for doing this nowadays, and PUTTY is the standard Windows application for the user end.
I've been using a Pi2 with a Hifi Berry S/PDIF output and a huge USB disk running Volumio to supply music at home for a year or two now. It works nicely enough, although a Pi3 might manage the large disk indexing better.
The Pi has 'I2S' support, which is the chip-chip digital audio standard, (when I first got involved there was no operating system support for this, so it was necessary to build a new kernel from source on a separate host. Nowadays it's put the card in the box and it just works. ) The Pi also supports I2C, which is a chip-chip control interface. So the DAC chip is configured via I2C and then the audio is played over I2S. If you configure the volume control in the operating system to the right type of 'digital' then I2C commands will be used to tell the DAC to change the volume, which is an ideal way to do it.
It's all so easy nowadays.
Paul