Thanks for deeper theory
, i was just checking would I able to gain any further quality if I use external DAC with SB3.

Err burr brown just makes the converter chip. The Odeon is a standalone external DAC which receives digital input using SPDIF and converts it to analog. How it finally sounds depends on a lot of factors in addition to the DAC chip - the power supply, the jitter rejection circuitry, the circuit topology, the output stage etc.