Should I get a DAC?

[baonam]

Hi, newbie question here. I recently bought the Topping L30 to use with the HD660S. I connect the L30 to the Xonar DX soundcard and found that I need to set the volume control at 2 o'clock with 0db gain to get it loud enough and sometimes I have to turn it close to the max. Is this expected without a DAC? It does sounds louder than just connecting the headphone directly to the Xonar DX, but should I be expecting the volume to be significant louder with just this amp alone? Do I need to get a DAC if I have to turn the volume control close to the max or something with my setup isn't right? Thanks in advance for your inputs!

 

[voodooless]

Why not use the high gain setting then? It adds 9dB, so should be roughly double as loud.

 

[baonam]

Why not use the high gain setting then? It adds 9dB, so should be roughly double as loud.

does setting the gain at 9dB the same as setting it at 0dB and turning the volume up to reach the same level of loudness? I found setting it at 0dB and turning the volume up sound better than setting it at 9dB.

 

[charleski]

does setting the gain at 9dB the same as setting it 0dB and turning the volume up to reach the same level of loudness? I found setting it at 0dB and turning the volume up sound better than setting it 9dB.

The standard design for an amp is
input -> attenuator (potentiometer referenced to ground) -> fixed-gain input stage that amplifies voltage -> output stage that provides current to drive the load

The gain of the amp is determined by the resistors used in the negative feedback loop on the input stage, this is probably what is changed by the 0/9dB switch. The volume knob is connected to the attenuator right after the input. There have been designs that have the volume directly changing the feedback that determines the gain of the input stage, but these can run into problems with stability.

So no, it's not the same. At 9dB gain the input stage sees a bit less negative feedback. But modern designs generally have such a large gain bandwidth product that this doesn't have much effect on the amp's performance.

 

[voodooless]

So no, it's not the same. At 9dB gain the input stage sees a bit less negative feedback. But modern designs generally have such a large gain bandwidth product that this doesn't have much effect on the amp's performance.

We don't have to speculate here:

I doubt you can hear a difference between the two. Sure, it will amplify the noise of the Xonar more, but that's the tradeoff for having it play louder.

 

[AdamG]

does setting the gain at 9dB the same as setting it at 0dB and turning the volume up to reach the same level of loudness? I found setting it at 0dB and turning the volume up sound better than setting it at 9dB.

Welcome Aboard @baonam.

 

[Veri]

I doubt you can hear a difference between the two. Sure, it will amplify the noise of the Xonar more, but that's the tradeoff for having it play louder.

Right. I don't believe 0dB and 9dB can sound different, really. Both are noise free and sound great to me.

 

[RHO]

What's the volume setting on your PC? Are you sure you are supplying the L30 with enough input voltage?

 

[baonam]

If I set the gain at 9dB, it gets respectably loud at 2 o'clock. So with all the inputs it seems that if I don't hear a difference in noise and distortion between 0dB and 9dB, I'm good without a DAC?

Right. I don't believe 0dB and 9dB can sound different, really. Both are noise free and sound great to me.

Does this still apply even without a DAC?

What's the volume setting on your PC? Are you sure you are supplying the L30 with enough input voltage?

I set all the volume settings on the PC and player to max. I used the 100-110V JP/US Adapter that came with the amp, other than that I'm not sure how to tell if it has enough input voltage or not.

 

[voodooless]

If I set the gain at 9dB, it gets respectably loud at 2 o'clock. So with all the inputs it seems that if I don't hear a difference in noise and distortion between 0dB and 9dB, I'm good without a DAC?

You won’t hear any noise or distortion from the L30, because it basically doesn’t have any What is left will be most certainly be the DAC. It has a SINAD of about 99, mostly noise dominant. I think you should be fine.

 

[solderdude]

I used the 100-110V JP/US Adapter that came with the amp, other than that I'm not sure how to tell if it has enough input voltage or not.

mains voltage is irrelevant as long as it is in the right ballpark. By that I mean one should not use a transformer designed for 230V on 110V mains.

When you can't get loud enough set the gain to H. There is nothing more to it than that. When it doesn't get loud enough even on H gain setting something is not set correctly on the computer side (volume control, pre-amp gain).
Chances are in H gain setting you may hear noise/strange soft background sounds etc. when no music is playing. This can be an indication of ground loops or other issues at the source (PC) side.

 

[charleski]

I set all the volume settings on the PC and player to max. I used the 100-110V JP/US Adapter that came with the amp, other than that I'm not sure how to tell if it has enough input voltage or not.

This is referring to the output level from the soundcard, and has nothing to do with the mains adapter. I don't know much about the Xonar DX, but a little googling shows that its control panel has several settings that will affect the voltage it's sending from its outputs, and you may want to play around with those to get the volume in a comfortable range. Try setting the analog output type to '2 speakers' and not 'headphones'. Alternatively, set it to 'headphones' and click the little hammer icon next to the field, then choose the 'Exciter mode' option. Turn the big volume knob in the control panel to its maximum and turn off Smart Volume Normalization, the small blue button on the left below the volume knob. Click the Mixer button in the panel at the bottom and ensure all the sliders are at the top.

 

[Shazb0t]

The Xonar DX is a DAC. You already have a DAC!

 

[baonam]

The Xonar DX is a DAC. You already have a DAC!

Yes, I knew the Xonar DX has a DAC, but from reading in the forum I see most people don't need to set their volume control pass 10 o'clock or 12 o'clock to get plenty of volume. But in mine case I need to set between 2 o'clock and max, so just wondering if I need a dedicated DAC or something is wrong with my setup

This is referring to the output level from the soundcard, and has nothing to do with the mains adapter. I don't know much about the Xonar DX, but a little googling shows that its control panel has several settings that will affect the voltage it's sending from its outputs, and you may want to play around with those to get the volume in a comfortable range. Try setting the analog output type to '2 speakers' and not 'headphones'. Alternatively, set it to 'headphones' and click the little hammer icon next to the field, then choose the 'Exciter mode' option. Turn the big volume knob in the control panel to its maximum and turn off Smart Volume Normalization, the small blue button on the left below the volume knob. Click the Mixer button in the panel at the bottom and ensure all the sliders are at the top.

The output was already set to 2 speakers", but the mixer sliders was only at 3/4 way, sliding all to the top did improved the volume. Thank you for this!

mains voltage is irrelevant as long as it is in the right ballpark. By that I mean one should not use a transformer designed for 230V on 110V mains.

When you can't get loud enough set the gain to H. There is nothing more to it than that. When it doesn't get loud enough even on H gain setting something is not set correctly on the computer side (volume control, pre-amp gain).
Chances are in H gain setting you may hear noise/strange soft background sounds etc. when no music is playing. This can be an indication of ground loops or other issues at the source (PC) side.

You won’t hear any noise or distortion from the L30, because it basically doesn’t have any What is left will be most certainly be the DAC. It has a SINAD of about 99, mostly noise dominant. I think you should be fine.

@solderdude , @voodooless, @Veri
Maybe it was the sudden jump in volume when switching from 0dB to 9dB that gave me the initial perception that 0dB is more comfortable. But after reading your guys inputs and listen to it for a awhile I think I'm comfortable with it now. H gain gives me plenty of power, so I think I'm good without a DAC. Thank you for assuring about the use of H gain setting