AMP vs DAC SNR + THD and DL200 vs AO300

[Zaviex]

Good morning everyone, my name is Riccardo and I am new to the forum and the world of sound systems. I have a question regarding the technical characteristics of a DAC versus those of an AMP: by comparing products of the same brand (e.g. SMSL) I noticed that the SNR and THD+N of ADCs or ADC+HF_AMPs are much better than those of amplifiers and I would like to understand why.
As an example I took DACs:
-DL200
SNR: XLR 130dB/HPA 125dB
THD+N: XLR -123dB/ HPA -120dB
-DO300
SNR XLR 132dB/ HPA 127dB
THD+N: XLR-124dB/HPA -120dB

while AMPs have
-AL200
THD+N: 0.003%
SNR: 107dB
-A0300
THD+N: 0.003%
SNR: 107dB

What is this big difference due to? I understand that an additional amplification stage brings in other components and thus more noise, but the difference is marked. Could it be that since the signal has already been preamplified by the DAC and therefore the noise introduced by the next stage affects it by a factor of 1/G_pre^2 then less weight is given to the noise introduced? If I measured SNR and THD+N using a DAC with active speakers after the internal speaker amplifier, would I have similar performance losses? Don't be afraid to get technical if you need to, in fact I prefer it
I take the opportunity to ask one last question:
I would like to upgrade my PC sound system by being able to take advantage of a pair of speakers and headphones(I already own Sennheiser HD-599s).
I am undecided whether to opt for
DAC/HP_AMP: DL200 + active speaker (e.g. 2 x Rokit RP5 G4)
or for
DAC/AMP/HP_AMP AO300 + passive speaker to recommend.

The initial question starts here, since the two components have very different characteristics.
I thank you all for your help and apologize for the stupid question.

 

[HarmonicTHD]

Good morning everyone, my name is Riccardo and I am new to the forum and the world of sound systems. I have a question regarding the technical characteristics of a DAC versus those of an AMP: by comparing products of the same brand (e.g. SMSL) I noticed that the SNR and THD+N of ADCs or ADC+HF_AMPs are much better than those of amplifiers and I would like to understand why.
As an example I took DACs:
-DL200
SNR: XLR 130dB/HPA 125dB
THD+N: XLR -123dB/ HPA -120dB
-DO300
SNR XLR 132dB/ HPA 127dB
THD+N: XLR-124dB/HPA -120dB

while AMPs have
-AL200
THD+N: 0.003%
SNR: 107dB
-A0300
THD+N: 0.003%
SNR: 107dB

What is this big difference due to? I understand that an additional amplification stage brings in other components and thus more noise, but the difference is marked. Could it be that since the signal has already been preamplified by the DAC and therefore the noise introduced by the next stage affects it by a factor of 1/G_pre^2 then less weight is given to the noise introduced? If I measured SNR and THD+N using a DAC with active speakers after the internal speaker amplifier, would I have similar performance losses? Don't be afraid to get technical if you need to, in fact I prefer it
I take the opportunity to ask one last question:
I would like to upgrade my PC sound system by being able to take advantage of a pair of speakers and headphones(I already own Sennheiser HD-599s).
I am undecided whether to opt for
DAC/HP_AMP: DL200 + active speaker (e.g. 2 x Rokit RP5 G4)
or for
DAC/AMP/HP_AMP AO300 + passive speaker to recommend.

The initial question starts here, since the two components have very different characteristics.
I thank you all for your help and apologize for the stupid question.

Good evening (I am about to go to bed ;-)) and welcome to ASR.

You already answered your question pretty much. Yes simply speaking it is mainly gain. Take a signal and amplify it by the usual 20 to 30dB. That “automatically” raises the noise floor and therefore decrease the SNR by that amount. The explanation is a bit simplified but as you said you would be new, I hope that explanation suffices.

Ask more as here are many experts which can also give a very detailed and complex answer ;-)

Good night.

 

[Zaviex]

Thank you for your reply! Sorry but I am not understanding, why for the calculation of SNR is it considered that the noise is amplified by the gain (rightly) and the signal is not?
What I don't understand is that if I considered the amplification stage as an ideal gain, both signal and noise would be amplified, preserving the SNR. Then removing the non-ideality, considering the noise of the amplification stage, if I were to calculate the total SNR referring to the input, the contribution of the second stage would be reduced by a factor of 1/G_pre^2. So either I have the amplification stages are much noisier than a DAC, which even considering the reduction they have a contribution of orders of magnitude greater, or I am missing something.

Thanks again and good night!