I am confused by the balanced and SE features of Topping's A50s and L50 headphone amps. I'm trying to pick one or the other to use with both very-low-impedance headphones and active speakers with balanced inputs. I'm thinking of Topping b/c of high current and power for low impedance HP, and price/value.
The L50 has a SE amplifier, according to Topping, and passes through pre-amp signals from DAC directly to external active speakers or amplifier (i.e. no pre-amp function). The A50s, unlike the L50, has a balanced amp, which also controls a pre-amp function, and has SE inputs. So here are my questions:
1. The L50 has a SE amplifier, yet has an XLR headphone output circuit. Does that mean that there is no doubling of the power to the headphones, but rather just a mechanism to pre-empt ground loops?
2. The L50 has a pass-through line-in/line-out for non-headphone outputs. But it also accepts balanced inputs. Does that mean that balanced inputs are no longer balanced when passed to an external device (non-headphone)? Or (showing my technical naivete, perhaps) is the pass-through somehow transparent enough to maintain balance from external input to amp output?
3. Since the A50s has RCA output connectors for non-headphone devices, there must be no way to use the A50s in balanced mode with active speakers, despite the balanced amplifier circuit ... am I right? (Topping doesn't explicitly say anywhere that balanced mode applies only to headphones with the A50s.)
4. With the L50, due to the pass-through, I assume the volume knob doesn't work with the pass-through signal, as it would with the headphone output. I guess that means that to control a powered speaker with, say, a PC's streaming input signal, the volume control for the whole system could only be the PC's volume control or an external DAC, if there is one?
And I assume the A50s, by contrast, could be the volume control for the whole system. (Or the DAC could if it has a volume knob.)
5. I know this has to be a hokey thought, but there's no way to use a 4.4mm balanced output to drive an active speaker in balanced mode, is there?
6. Topping's literature doesn't explain this all very well, except to hint that the L50's pass-through feature makes it somehow advantaged to use with active speakers ... Although elsewhere, Topping says the A50s (with SE outputs to active speakers but with a pre-amp function) is just dandy to use with active speakers. What's the deciding factor?
The L50 has a SE amplifier, according to Topping, and passes through pre-amp signals from DAC directly to external active speakers or amplifier (i.e. no pre-amp function). The A50s, unlike the L50, has a balanced amp, which also controls a pre-amp function, and has SE inputs. So here are my questions:
1. The L50 has a SE amplifier, yet has an XLR headphone output circuit. Does that mean that there is no doubling of the power to the headphones, but rather just a mechanism to pre-empt ground loops?
2. The L50 has a pass-through line-in/line-out for non-headphone outputs. But it also accepts balanced inputs. Does that mean that balanced inputs are no longer balanced when passed to an external device (non-headphone)? Or (showing my technical naivete, perhaps) is the pass-through somehow transparent enough to maintain balance from external input to amp output?
3. Since the A50s has RCA output connectors for non-headphone devices, there must be no way to use the A50s in balanced mode with active speakers, despite the balanced amplifier circuit ... am I right? (Topping doesn't explicitly say anywhere that balanced mode applies only to headphones with the A50s.)
4. With the L50, due to the pass-through, I assume the volume knob doesn't work with the pass-through signal, as it would with the headphone output. I guess that means that to control a powered speaker with, say, a PC's streaming input signal, the volume control for the whole system could only be the PC's volume control or an external DAC, if there is one?
And I assume the A50s, by contrast, could be the volume control for the whole system. (Or the DAC could if it has a volume knob.)
5. I know this has to be a hokey thought, but there's no way to use a 4.4mm balanced output to drive an active speaker in balanced mode, is there?
6. Topping's literature doesn't explain this all very well, except to hint that the L50's pass-through feature makes it somehow advantaged to use with active speakers ... Although elsewhere, Topping says the A50s (with SE outputs to active speakers but with a pre-amp function) is just dandy to use with active speakers. What's the deciding factor?