If your are looking for a cost-effective alternative of HiFiBerry, a board with more options (e.g. very-low-noise DAC LDO or to power RPi and your extensions, to have P1 connector free on RPi) - please check this out:
http://www.tjaekel.com/T-DAC/raspi_rca.html
Hi. Just interested - why the PCM5102 instead of the PCM5122? 
Hi Pete,
major reason why PCM5102 and not PCM5122:
- it has an option for “PLL mode”: RPi does NOT generate MCK (or SCK). The DAC can be configured (SCK tied to GND) in order to generate this signal from BCK. Pretty nice and really mandatory feature for RPi. PCM5122 does not have it.
- Even, it is a bit cheaper and has less pins (easier to solder, smaller).
Not tried to use the PCM5122 but the issue is: RPi provides just BCK, SCLK and DATA, not SCK/MCK. But many DACs need this system clock
(BTW: PCM1794A works also nice via SCK = BCK, other DACs … no guarantee and not tried all others).
Another reason is:
PCM5102 provides a HW mode, all can be configured via pins and soldering on PCB and DAC pins. No I2C or SPI communication needed.
The PCM5122 needs I2C or SPI communication which is necessary in order to enable, configure etc. the DAC. It results in:
RPi has to talk via I2C to DAC, P1 allocated for I2C, driver in Linux kernel needed, not transparent (RPi-DAC-RCA can use the HifiBerry as well as the RPi-DAC driver).
RPi-DAC-RCA does not need anything on P1, P1 remains free (different to HifiBerry which blocks P1), no Linux driver development or installation needed, I2C remains free for something else, e.g. your extension boards.
Thank you very much for the great explanation. I will post your link on Rune Audio too (Hope you don’t mind). 
Err, not sure the previous email is 100% accurate about the PCM5122.
PCM5122 does have the built in PLL - the PCM5122 is the much more modern equivalent to the PCM5102A. The TI Product manager for these devices is an ex-colleague.
PCM5122 can act as I2S slave or master.
PCM5122 has built in HW volume control.
The PCM512x has a Linux driver built in to Raspian - I worked on it!
The PCM5122 can be hardwired or controlled by I2C / SPI.
The PCM5122’s big brother is the PCM5142 - has additional features and once more - better audio qualities.
If you want to read more then head over to TI’s web site and do a simple comparison.
Not sure anyone will read this, but PCM5122 and PCM5102A are identical DAC’s, one is HW
controller the other SW. IN addition the PCM5122 has HW volume control, but it is digital
not analog, so I’m not sure it’s worth. Besides, any downstream device that gets the audio
will have it’s own volume control, usually analog.
mike