I have just spent 4 days in my house judging the sonic differences between I/U transistors in the SW1X DAC. Slawa supplied the DAC and 6 sets of PNP resistors with a circuit board set up so that each could be plug and played.

Well those sceptics that claim all components sound the same can turn away now.

My criteria was not about Hi Fi qualities such as extended bass, or fuller mid range, but more about was I really enjoying the sound, would it keep me listening late into the night, and if there were 6 DACs separately fitted with just one of the pairs of trannys, which would I buy?

Slawa had pre selected the six trannys from a host of candidates ranging from rare 1960s stuff to modern equivalents, some silicon and some germanium. I wont go into detail, but suffice to say that marking out of 10, the worst got 4 and the best got 9. Differences were not subtle.

I use this just as an example of how one component in a circuit can influence the sound of the final product. Slawa tests most components in this way