Matching preamp/amp

[imackify]

I have to admit I don't really know how the output voltage and input sensitivity works on components.

So I ordered a Topping DX5 for my computer to output to my Sennheisers. I have speakers in the office as well that are in need of an amp.

I'm considering https://www.audiophonics.fr/en/powe...reo-amplifier-ncore-2x250w-4-ohm-p-14185.html

My concern is the XLR from the Topping is 4.2Vrms but the amp says its full power is at 1.66 Vrms (2x0.83Vrms) input...is the topping output too much or is this really nothing i need to worry about?

 

[Blumlein 88]

At max volume the Topping would over-drive the amp by about 8 db. You'd have to turn it down 8 db to not overdrive or clip it. As you have 120 db of dynamic range in the Topping I don't think it would be a problem for sound quality. You'll likely turn it down another 15 db or so for listening depending upon how much power your speakers really need. Again I don't think it will be negative for sound quality. The only issue is if the DAC accidentally comes on at full volume with a signal playing. That amp likely would trigger a protection circuit if that happened.

Is it not common to find DAC/preamps with less than 4 volt outputs when using XLRs. I've used a similar arrangement for several years and never had an accident. It can happen.

You also could use the RCA output of the Topping with an adapter to XLR. Then you'll get 2.1 volts output max. Kind of a shame to do that, and it could cause a chance of a bit of hum.

 

[DVDdoug]

It's common for the preamp (or other devices) to have "headroom". You don't want the opposite situation where you can't utilize all of the power from your power amp or headphone amp.

 

[restorer-john]

Far too much illinformed obsessing over 'matching' D/A output levels to power amp input levels on ASR. Utterly pointless and completely wrong practice. Especially as the source content levels wildly vary.

Preamplifiers (proper ones) have a rated output (for a given input voltage) and a maximum output. They are poles apart. By many volts. A preamplifier may have a 200mV sensitivity for rated output of 2.0V. But it may happily put out 20V if you feed in 2.0V. Or it may clip at 3V (300mV in)- you need to test it to find out. No guesswork will help.

Power amplifiers have a rated input sensitivity (in volts) for full rated output (in watts over a specific load impedance). The power amplifier may be able to swing considerably more than its rated output, sometimes continuously, sometimes just for a short period, but that can mean all the calculations in the world end up meaning nothing other than mainly leaving a whole lot of gain on the table and missing out on what your combination can achieve.

And, to @Blumlein 88 's point. For goodnes sake, turn down the volume of the preamplifier before turning on your power amp! Don't rely on anything remembering the last setting.

 

[Blumlein 88]

And, to @Blumlein 88 's point. For goodnes sake, turn down the volume of the preamplifier before turning on your power amp! Don't rely on anything remembering the last setting.

I do just what you say. Turn the source and preamp on first, and turn it down. Repeatedly however, I've seen others no matter how many times you remind not do that. It is more dangerous if you have your phones on and it goes full volume on you. Dangerous to your ears.

In the case of the gear the OP is using, it is a DAC/preamp/phone amp. So it isn't putting out 20 volts. It doesn't even have an analog input. It is putting out no more than 4.22 volts. Now I would be fine with it. Some people do obsess over it.

What you describe is right for old analog preamps. I had tube units that were rating for 4 volts out at 200 mv in, and could at max gain output 40 volts if fed 2 volts from a CD player. The other end of wasted gain.

 

[imackify]

Great info thanks everyone. I really just wasnt sure if it was something i needed to worry about as i only ever bought from same company before.

And i guess the only issue would be as per @DVDdoug, the oposite problem, pre having no headroom and not utilizing amps potential.