Would I be wasting my money to get a turntable?

@audiotroy the M33 accepts a digital signal, uses Dirac, then has a DAC, then an Amp.

Jerry

In class D amplifier "Voltage" is converted to "Duty Cycle", both analog - meaning there is no discrete steps (unlimited resolution). Duty cycle is back-converted to (amplified) voltage by filtering. Streaming and CDs both have limited resolution (16 bit in CDs).

What happens when your PWM’s oscillator signal frequency is not high enough? Who determines what frequency is "enough"? The resolution is not infinite unless the frequency is infinite (impossible). This is at least vaguely analogous to the sampling rate in digital quantization. Then you have the output filtering to smooth out artifacts from a finite frequency oscillator, and this is analogous to that phase of DA conversion.

Guys we are an NAD dealer the m33,does indeed digitize an analog signal in order to use DiRAC Room Correction for all sources.

so your answer is the analog input will sound different then streaming but if you want to hear the best in analog I would trade in the m33 and go up up to the nad M66 which has a true analog Preamp as well as an improved dac.

Dave and Troy Audio intellect NJ

Nad masters  dealer

What do you call the conversion of an analogue signal to a PWM/PDM or ΔΣ modulation and its subsequent filtering to recover an amplified analogue signal? Because if that’s not digital, then CD is not digital and streaming is not digital either. However, that’s exactly what happens in a class-D amp, at some point. The filtering is at the very end, but the signal conversion can happen at the amp input or just before the final (current) amplification stage.

In class D amplifier "Voltage" is converted to "Duty Cycle", both analog - meaning there is no discrete steps (unlimited resolution).  Duty cycle is back-converted to (amplified) voltage by filtering.  Streaming and CDs both have limited resolution (16 bit in CDs).

@carlsbad2 Tell us more.

@glennewdick

there is no digital (I.e. code) in a class D amp, period. your confusing the differences here.

I’m sorry, but the one who is confused is you. The technique used in class D (which I agree does not stand for ’Digital’) is the same PWM (or other pulse-based modulation) used to convert an analogue signal into a digital stream for CD or other digital medium and back into an analogue format. Neither more, nor less. If there are ’digital sound quality’ issues due to quantization or filtering, they would emerge in this transformation neither more nor less than in an ADC converting an analogue signal.

The fact that potentially the only operation performed on the pulse stream so obtained in a class D amp is amplification, and it is not treating the digital stream in other ways, is neither here nor there: they are 1s and 0s whether you like it or not: the transistor is either saturated or cut-off, and in fact any use in the linear zone is not only not-favoured; it is discouraged and unwanted. The analogue signal is not recoverable unless you use the same techniques to demodulate and filter the pulse stream that are used in a DAC (obviously with much higher currents and voltages, but again that is irrelevant).

I’d suggest you get a degree in EE, then perhaps we can google together from the same basis of understanding.

I am  shocked by some of the misunderstanding about class D out there. 

Jerry

I think it’s not so black-and-white whether class D is or is "not" digital. Sure if you’re getting into a semantics war, it doesn’t meet the criteria of digital quantization and conversion. But some of the elements / patterns are certainly there, and I think @dlevi67 is correct to point them out.

Anyways, in true Audiogon fashion, this sidebar isn’t even fully relevant to OP because the preamp stage of his M33 converts ALL analog inputs to digital (ADC), before it even hits the class D amp stage. Maybe it can directly convert that to the necessary PWM without an intervening DAC stage - that might mitigate the issue I had with the separate M12 + M22 combination's SQ?

The sound quality you get is a result of the components you choose. If you choose poorly you can get vinyl that sounds harsh and trebly and digital that is warm and musical... although it is still easier to get the opposite as cheap components tend to favor the more forgiving vinyl. 

Since you can craft digital or vinyl to sound which every way you like, there is just no advantage to vinyl any more. If you have dollars that you can invest in analog... invest in getting better digital. 

So, it has an ADC/DAC in it?

A lot of folks on line, even some learned ones thinks the ’D’ stands for digital and writes as if the amp is when as far as I can tell when delving a bit into it isn’t correct.

dlevi67, "What do you call the conversion of an analogue signal to a PWM/PDM or ΔΣ modulation and its subsequent filtering to recover an amplified analogue signal?"  

yes analogue still. no ones and zeroes involved here so not digital.  

there is no digital (I.e. code) in a class D amp, period.  your confusing the differences here. Class D has been around since 1958 well before digital anything was a thing in Audio. I'd suggest you do a google search and read up on the differences, class D was just the next letter in the alphabet after class C. 

@glennewdick 

One class D is not digital in anyway

What do you call the conversion of an analogue signal to a PWM/PDM or ΔΣ modulation and its subsequent filtering to recover an amplified analogue signal? Because if that’s not digital, then CD is not digital and streaming is not digital either. However, that’s exactly what happens in a class-D amp, at some point. The filtering is at the very end, but the signal conversion can happen at the amp input or just before the final (current) amplification stage.

Would I be wasting my money to get a turntable?

if you hook it up, turn it on, put albums on the platter, drop the needle and it produces sound, no, no you won’t be wasting money. Just don’t skip any of the above...

One class D is not digital in anyway,

Two his amp has room correction software so if he is using it yes its digitizing all inputs regardless.

Three if you dont' have records already i would pass on them its expemcive to do well, takes up considerable room, takes a long time to accumulate records, new records are expencive. If your a collector type maybe records are for you. 

My amp gives me the option of converting the signal to digital or keep it analog. Digital conversion sounds better.

Digitizing itself isn’t going to kill the vinyl sound; I’ve had quite good results with Meridian 808i DAC / preamp units that digitize all analog inputs input and apply DAC / filtering on output - even with very high end vinyl gear. It can be suprisingly transparent. The main thing is that if you're used to a tube preamp, you won't get its added warmth and fullness from any digital preamps (as line stages they are a bit clean and dry) - though you COULD pipe the digital preamp into an input of a tube preamp...

That said, I also had the NAD M12 digital preamp and did not like its sound, at all. The M22 amp was fine, but the M12 did not make the cut here - I think even their older M51 DAC might have been better.

The basic answer is ’energy efficiency’ - by converting the (voltage amplified) signal into a PWM (or other modulation technique) signal, and then filtering that PWM to retrieve the audio signal, the transistors in the final stage are always ’open’ or ’closed’, thus dissipating minimal energy.

Note that in many power amps the analogue-to-digital conversion happens only at the final power stage, which is where ’traditional’ amps consume most energy, however the NAD seems to convert phono signals to digital earlier than that.

So, this thing takes an analog signal, digitizes it, then converts it back to analog?

Why?

@carlsbad2 + 1

Perhaps the Sugar Cube example provides insight into this question.  A Sugar Cube is a gadget that removes clicks and pops from scratchy or otherwise noisy records.  It does this by making an instantaneous copy of the music digitally, automatically editing out the noise, and then allowing the cleaned up signal to be amplified and played.  The user can compare before and after to hear what the effect is both of the noise reduction and of digitization of the musical signal.  It is so effective that many users simply leave it on full time.  In other words the digitization of analog signals as a serious degradation of purity is greatly exaggerated.  There is no reason for you to deny your desire to add a turntable and records to the enjoyment of your hobby.

From a technical perspective the question here is does the amplifier have an internal analog to digital converter which takes the analog signal in the preamp stage and converts it to digital and outputs the digital signal.

  Amplifiers can have digital power stages and the common designation for this is Class D amps.  However, if fed an analog signal, which is then amplified, that isn’t the same thing as as changing an analog source to a digital source.

  I don’t know enough about the NAD amp to answer the first question but I have heard of amps that do place the analog signal in the digital domain.  If indeed that is the case with the NAD then I think the OP has asked a fascinating question .  And as other posters have indicated it will still probably sound very good.  As a practical matter if he has a large collection of LPs that he wants to play.  If the answer is no, and he is starting from scratch, I would stick with streaming or CDs, because it’s all going to end up as a digital waveform 

If you don't already have a fair number of vinyl records, it's not worth it in my opinion.  I spent $4500 to get a decent cartridge, TT, and phono preamp. That's a relatively inexpensive setup.  It sounds great, but not better than streaming.  A few albums do.  But, take a look at what good vinyl costs.

Class D is not digital. It does not digitize the analog input. I am all streaming but my friends who do vinyl are very emotionally attached and enjoy it tremendously. What amp you use is not a factor. Looks like your amp has a phono input so you don’t even need a phono pre.

Jerry

@gregm +1 - I should have been more explicit! 

As above and more to the point, do you have an LPs collection to play & listen to?

I think the key question here is 'what would you listen to on the turntable?', rather than 'can it sound good?'

The answer to the second question is yes, provided you choose a good turntable and set it up well. Would you get an improvement in sound quality vs. a good digital streaming source, properly set up? IMHO, no, but to some extent 'sound quality' is subjective.