BoredErica
Addicted to Fun and Learning
Since Topping Pa5 nuked itself and Topping probably can't guarentee a fix that won't have the amp failing in the same way again, I don't think I want to pay shipping to Topping to get it fixed. (This is a little sad given allegedly the cause for early failures was discovered.) Now I need a new amp. Setup is: Computer -> Motu M4 -> Topping Pa5 -> Ls50 Meta. Also have a Rythmik F12se sub connected to the Motu M4. The concern once again is noise. Ideally no noise could be heard with ear at tweeter but I can settle for inaudible noise at a very quiet room at 20in from tweeter if I feel like I must. Volume adjustment is done digitally. With pa5 due to the low gain, I felt noise was inaudible w/ ear at tweeter. (19db gain. I could turn my M4 all the way up past 5v output.) I live in US and I need everything in the chain to be balanced.
Options:
Buckeye Purifi: $1037 + $45 cables or $12 TRS->XLR Converter
Motu M4 caps out at 5.24v output so can't hit the spec for low gain but I assume that's ok given my low power requirements. 20.5dB/4.02Vrms (Medium), 15.5dB/7.16Vrms (Low). On bright side, 15.5db gain is good and Purifi is not known to have longevity issues despite being widely used. Anyways, since 19db gain was OK, 20.5 should also be OK. So this should be perfect ignoring cost.
Topping LA90 Discrete: $812
Buying from APOS so I don't have to send defective unit to China. 19.25db/2.2v high, 9.3db/7.3v low. This is like a cheaper Purifi in that noise can't be an issue. But it's Topping, so... uh... Well, at least original LA90 has been out for over a year without a thread of people complaining. This is the LA90 Discrete though.
Buckeye nc252MP: $545 + $45 cables or $12 TRS->XLR Converter
There is a chance I would want a preamp to fix the 25.5db gain which is too high. But what preamp would that be? I have a Mayflower o2+odac combo but I don't think it works as a preamp. Even w/ preamp, nc252MP should still be cheaper than Purifi. [-10db XLR attenuators also an option? $31 cost. Adds bulk and attenuates by fixed amount, but cheap and are unlikely to break.]
Topping Pa7: $465
I don't like this option. Linearity is a little suspicious. It's like a more expensive, less well-performing Pa5 that hopefully has Pa5 issues fixed. It's the cheapest though.
My assumption is if an amp's gain is low, the voltage the amp requires increases. If my M4 can't outfit high enough voltage, what happens is I don't get full max specced power from the amp but apart from that nothing funky/crazy happens. Another idea: Wait until Buckeye has a sale and live with 1 channel audio. I lived over a year with 1 channel, surely I can survive several more. ...right?
Most of the noise comes from dac due to gain of the amp, so if I can reduce gain somehow I believe this will reduce noise. If I can't have an amp w/ adjustable gain, then I think I can use a 2 channel preamp to functionally reduce the gain on a fixed gain amp. Noise comes from mains and not the sub. Volume knob on Motu M4 is digital and suboptimal. I want to keep that at max. If I have an amp w/ 25db gain and I want 15db, the idea is the preamp would functionally act as -10db gain and -10 + 25 = 15db. Correct me if I'm totally wrong.
Power requirements I assume are low. I still have no idea how to actually measure how loud my music is even with a calibrated mic. Years ago I used an A weighted cheapo SPL meter and got 70-75 at high end. I do have a sub. Let's assume 15-20db DR tracks? I think that is safe. 5-10db EQ headroom. Sitting up to 6ft away. LS50 Meta. I think even LA90 will suffice.
So: Which amp to get? If nc252mp and noise is audible, how to attenuate signal before it hits the amp? I don't need a headphone amp. Or... send Pa5 to china and pray Topping fixes it. (Some say after repair attempt it was fine, some say it broke again.) I'm going to need therapy if after going through noise-induced hell and jumping into a failing amp, the next amp breaks in 5 years. Is it unrealistic to expect 10yr operation?
Options:
Buckeye Purifi: $1037 + $45 cables or $12 TRS->XLR Converter
Motu M4 caps out at 5.24v output so can't hit the spec for low gain but I assume that's ok given my low power requirements. 20.5dB/4.02Vrms (Medium), 15.5dB/7.16Vrms (Low). On bright side, 15.5db gain is good and Purifi is not known to have longevity issues despite being widely used. Anyways, since 19db gain was OK, 20.5 should also be OK. So this should be perfect ignoring cost.
Topping LA90 Discrete: $812
Buying from APOS so I don't have to send defective unit to China. 19.25db/2.2v high, 9.3db/7.3v low. This is like a cheaper Purifi in that noise can't be an issue. But it's Topping, so... uh... Well, at least original LA90 has been out for over a year without a thread of people complaining. This is the LA90 Discrete though.
Buckeye nc252MP: $545 + $45 cables or $12 TRS->XLR Converter
There is a chance I would want a preamp to fix the 25.5db gain which is too high. But what preamp would that be? I have a Mayflower o2+odac combo but I don't think it works as a preamp. Even w/ preamp, nc252MP should still be cheaper than Purifi. [-10db XLR attenuators also an option? $31 cost. Adds bulk and attenuates by fixed amount, but cheap and are unlikely to break.]
Topping Pa7: $465
I don't like this option. Linearity is a little suspicious. It's like a more expensive, less well-performing Pa5 that hopefully has Pa5 issues fixed. It's the cheapest though.
My assumption is if an amp's gain is low, the voltage the amp requires increases. If my M4 can't outfit high enough voltage, what happens is I don't get full max specced power from the amp but apart from that nothing funky/crazy happens. Another idea: Wait until Buckeye has a sale and live with 1 channel audio. I lived over a year with 1 channel, surely I can survive several more. ...right?
Most of the noise comes from dac due to gain of the amp, so if I can reduce gain somehow I believe this will reduce noise. If I can't have an amp w/ adjustable gain, then I think I can use a 2 channel preamp to functionally reduce the gain on a fixed gain amp. Noise comes from mains and not the sub. Volume knob on Motu M4 is digital and suboptimal. I want to keep that at max. If I have an amp w/ 25db gain and I want 15db, the idea is the preamp would functionally act as -10db gain and -10 + 25 = 15db. Correct me if I'm totally wrong.
Power requirements I assume are low. I still have no idea how to actually measure how loud my music is even with a calibrated mic. Years ago I used an A weighted cheapo SPL meter and got 70-75 at high end. I do have a sub. Let's assume 15-20db DR tracks? I think that is safe. 5-10db EQ headroom. Sitting up to 6ft away. LS50 Meta. I think even LA90 will suffice.
So: Which amp to get? If nc252mp and noise is audible, how to attenuate signal before it hits the amp? I don't need a headphone amp. Or... send Pa5 to china and pray Topping fixes it. (Some say after repair attempt it was fine, some say it broke again.) I'm going to need therapy if after going through noise-induced hell and jumping into a failing amp, the next amp breaks in 5 years. Is it unrealistic to expect 10yr operation?
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