This BPA300v2 is almost the same as my original BPA300 except I used the Lundahl 1545a to replace the DRV134. There are a few advantages :
- Power regulator is no longer needed
- The 15uF input capacitor can be removed because input transformer can block DC
- Improved Noise CMRR
- The transformer isolate the power amp from the pre amp electrically, i.e. ground loop breaking
- Easily support RCA and XLR input
No power needed for the Input transformer, save some components
By using input transformer, the BPA300 can support RCA and XLR input easily. No switch required.
No input capacitor is needed, more transparent sound.
One disadvantge with input transformer is that an active preamp should be used, otherwise there will be high frequency roll off. See my LL1545a measurement page for details.