It seems that Mate 16.04 has been set up to accommodate HATs like the HiFiBerry Amp with the overlay hifiberry-amp-overlay.dtb so I thought it would be fairly easy even with my limited ability … but not so 
I have added to the config.txt:
dtparam=audio=on
dtparam=i2s=on
dtparam=spi=on
dtoverlay=hifiberry-amp
dtdebug=1
I checked etc/modprobe.d/blacklist-rpi2.conf
‘#’ blacklist snd_soc_pcm512x_i2c
‘#’ blacklist snd_soc_pcm512x
blacklist snd_soc_tas5713
‘#’ blacklist snd_soc_wm8804
‘#’ blacklist snd_bcm2835 (I switched this back on so that I could confirm sound output via HDMI)
when running: aplay -l to check if hifiberry has been found I do not see it listed!
This has stopped me doing the last steps suggested = creating etc/asound.conf
The hifiberry-amp+ works fine with PiMusicBox & Volumio so I know the hardware is good.
As MATE boots and writes beneath the Raspberry Pi logos I see that HiFiBerry appears, but the boot is too quick to read the lines & I don’t know how to pause the boot process.
… but I clearly need to do more and would appreciate help.
Cheers
Charles
P.S. similar to older post