D10 (I chose this)
- PRO: easy PC connection with only USB, no power-cord
- PRO: up to DSD256 and up to PCM 384kHz/32bits, so unlikely that any useful audio format won't play
- PRO: more "modern" ESStech ES9018k2m chip (ES9018 is from 2010/2011, the k2m from 2013)
- CON: no other digital inputs
- CON(maybe): no detailed information on how DSD is handled
D30
- PRO: power switch + separate power supply if you want to power it with something special
- PRO: coax and toslink inputs
- PRO: can do DSD direct, i.e. bypass all processing (DSD volume + 50kHz filtereing optional)
- CON: massively older CirrusLogic CS4398 chip (2003)
- CON: no 32bit PCM, i.e. digital attenuation is less accurate
They measure about the same (SINAD ~105dB) so both will probably be audibly transparent.
My choice was to go for simplicity (USB powered) and that fancy D10 screen
When connecting to a Pi check your power supply: according to specs the Topping D10 will use about 0.5A out of the USB port... I hear the "official" wall-wart is a little under-powered! This also depends on your Pi generation, e.g. v4 likes more juice more than v3, which in turn drinks more than v2.