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NM24 Instructions


NM24 Operating Instructions

1: Please inspect for shipping damage: there are two large and heavy toroidal transformers inside, securely anchored onto the chassis. But there is still a
possibility they might come loose during shipping.

2: The tubes should also be securely seated into their sockets. Use a soft micro fiber cloth to reseat the tubes. Do NOT leave finger prints on the glass surface. If you do leave some finger prints on the glass surface then use a very soft cloth (micro fibre) to clean the tube. DO NOT use any chemicals such as Windex, vinegar, etc. to remove the prints.

3: The unit generates a large amount of heat due to the four tubes. Please ensure good ventilation for long term reliability. Never stack other components on top of the NM24.

4: WAIT 2 MINUTES! The tubes need 2 minutes to warm up. A relay will then kick in to allow the audio signal to pass through. The Volume should be set LOW (about 9 O’clock) so the output signal will not suddenly blast into the Power amp/Speakers.

5: BOTH the Solid State DAC output and the Tube DAC output can be used at the same time. The SS DAC out is usually connected to a subwoofer with levels controlled by the settings of the subwoofer. When the desired bass output is set on the subwoofer, usually there is no need for further adjustments even the main output level is adjusted.

6: The Tube DAC Output is internally connected to the volume control via the Push button switch near the volume: Button OUT is for Tube DAC
Button IN is for connection to the signal at “Line IN”. If the Tube DAC Out is connected to an external preamp or line amp, it is advisable to push this button IN so that the tube DAC signal is not shared by an unnecessary load (the internal line amp)

7: The Line Amp is a high performance all- tube unit capable of driving any power amp or headphone. If headphones are used, it is advisable to unplug the wires from “Line Out” of the unit to avoid unnecessary loading . If the Line Amp is used to drive a power amp, the headphone should be unplugged
for the same reason.

8: We recommend high impedance headphone such as the Sennheiser HD650 (300 Ohm ) or BeyerDynamic DT990 (250 Ohm). Although a low impedance headphone such as the Grado SR-80 can be plugged in it is preferable to use a step down transformer to convert 300 Ohm to 32 Ohm.

Block Diagram

NM24 block diagram

Setting-Up the NM24

In the photos below, we will illustrate how to set-up the NM24 while using the DIP Combo. In the system below we are using both a Mac Mini and a CD Player as inputs (right). The Mac Mini is using an optical cable that plugs into the Mini's headphone jack and then into the DIP. We also have a CD connected via a Coax cable. You can choose the source of input on the front of the DIP. In our case, select Opto for the Mac Mini and Line for the CD player.


In the photo above you can see where we have the Coax of the DIP going out to the the Coax of the NM24 (below). If you are not using a DIP, then you can use either an optical or coax cable to feed into one of the Digital Inputs below.

nm24 input

Note: The two pairs of "Analog Outputs" above may be used with the headphone jack. It is important that if you are using either of these for your headphones and have an amp plugged into the Line Out (below) that you do not use the Line option (on front of NM24) to power your power amp. The headphone adapter should always be unplugged from the NM24 if power amps are used. This avoids loading  down the signal level that might affect sound quality.



In the image above we are using the Line Out to drive a power amp. If you wish to bypass the NM24 DAC, then you can plug your component directly into the Line In (above) to use the NM24 solely as a pre-amp. Note: Always power down all components and let them set a few seconds before connecting any interconnects. Begin by powering down components closest to the speakers and working back to your audio source.


High-resolution PDF of the rear connections Opens in new Window

If it is difficult to read the text above then here is the original draft:



The New NM24

With the latest NM24 we use the Line Stage to create an audiophile tube headphone amp unparalleled in quality. The jack is on the back of the component. In the past we have recommended one headphone: Sennheiser HD650 (300 Ohm.) Recently, another headphone has caught our attention: The German made Beyerdynamic DT990 (250Ohm). This headphone works exceptionally well with the NM24, and be purchased on eBay for around $200. Besides its superior audio quality, it has a comfort level that few others can match.

Adaptor for Older Monarchy DAC's

Many audiophiles already know that the Model 22C and Model 24's Line Amp output has enough drive for all dynamic headphones.

The Line Stage actually outperforms all headphone amps on the market.

But a simple RCA to phone jack adaptor has to be used to connect the headphone directly to the Line Amp's output.

We supply such an adaptor to owners of the Model 22C and Model 24 for just $10 plus $5 shipping/handling(total $15). Attached picture shows
a headphone also, not included in this price.

M22C has a very low output impedance(about 50 Ohms) to drive any headphones.

M24's Line Amp output impedance is 300 Ohms and is perfect for higher impedance headphones like the Sennheiser HD650.

A step down transformer per channel would be required for lower impedance headphones such as Grado's SR60 or RS-1. Please contact factory for such arrangements.

Using a high quality headphone will immediately convince all Monarchy DAC owners the spectacular performance from these Line Out's.

Modding the NM24

One of the first things the DIYer wants to do is modify the coupling caps found in the NM-24. It should be noted that the NM-24 has evolved to what it is today through years of testing, fine tuning, and factory modifications. We feel that in its current form that there is little that can be done to improve the sonic quality of the NM-24. Regarding the WIMA caps, first read this article and decide if it is worth the cost to upgrade the coupling caps WIMA Capacitors. But, there will always be some who want to get their hands in the mix. So, let us begin with the easiest.

The easiest "Plug and Play" upgrade would be to replace the existing tubes with Telefunken ECC88. But, a set of four tubes will cost you $1,800! This link describes the tube and the video at the bottom of the page explains the different grades and prices.

Obviously, the straight forward upgrade is a bit out of range for the typical listener. We will, overtime, provide you with some simple upgrades that will add to the transparency and sonic quality of the NM24.

Isolation Feet

One of the easiest and cheaper mods that one can to do any audio gear is to add some isolation feet. Monarchy Audio currently has a very limited supply of nickel isolation feet.

Isolation feet. Set of 4 for $20.isolation feet

Applying: The double sided adhesive tape may not be as good as new, due to aging. This can easily be replaced. The base of each piece is approximately 3/4" X 3/4", and the height from tip to bottom of base is 3/4".
The best way to use these feet is to 1) mount them to the audio component using double sided tape, 2) place a USA Nickel, heads-up, on the surface where the feet will be used. The raised edge of the US Nickel will provide additional isolation on any flat, hard surface. If desired a small "hole" can be partially drilled in the center of the Nickel.

The Monarchy NM24 Weekend Warrior Modding the NM24 DAC!

Tubes and Cap Mods

There are 2 mods that used by the DIY community. You can upgrade the tubes if you like, but the biggest bang for the buck is in upgrading the coupling caps. Below are some conversations pulled from some forums describing the mods and their impact on the listening experience. We have included an image of the cathode caps.

Compared to the original Philips tubes, the Svetlana tubes sound more detailed, "airy," three-dimensional, and much more dynamic. The sound stage is MUCH wider and deeper, as well. When I went back to the Philips tubes, the sound seemed "dull" and flat. Overall, for me, the difference is very obvious.

I have a modded Monarchy NM24 DAC....very well designed can replace the stock DAC side tubes with Amperex NOS and will be a great improvement. But the best mod is to replace the 2.7uf Wima MKP coupling caps with Mundorf M supremes 2.7uf caps. It is a tight squeeze but they fit and the difference is a jaw dropper. Crystal clarity,the best bass I have ever heard ...tight,well defined and powerful,Midrange is smooth as silk, and imaging that is pinpoint. But the kicker is the perceived power and weight of the like tripling the power supply .....a winner.

Also I increased the gauge size of the wiring.

The tubes cost me $150 on E and the caps are $60 for 1400 I got a truly killer DAC.


NM24 Cathode Caps

So I then came across a post where the same DAC was modded where the coupling caps were replaced. This DAC uses 2.7uf 400v Wimas....not bad but there is better ....Mundorf 2.7uf 800V were used in place of the Wima's. The poster said he thought the DAC was transformed and sounded better than DAC's costing thousands more.

Being the tweaker that I am ....I tried it.....He is right ...A richness that sounds like very good analog and focus and clarity magnitudes better. But the big difference was the feeling of presence that is created ...Wow. Right now I'm using my SS amps in place of my tube amps....but after this change even the solid states sound warm and rich.

Most Recent Cap Modding

Below is from an email:

Recently a customer brought over a NM24 that had the Mundorf Silver foil/Oil upgrade  done by a mod guy
in Sacramento.

I was amazed at how much  more music could come out of the NM24, having listened to this model virtually every day
for the past 5 or 6 years.

I had actually advised customers not to do it, because the Mundorf cap is so big(much bigger than a Size C battery), the only way is to dangle them underneath the top cover, with wiring connected to the pcb, which might induce hum and noise.

But this mod guy chose a much smaller value (1uf) and yet there didn't seem to me any loss in the low frequency, which I was afraid 
might happen (original value 3.3u). Only this small value could be directly mounted on the pcb (after the WIMA caps removal)

The sound is so much more musical, more life like, more dynamic, I am absolutely convinced it is a very worthwhile  upgrade.
(this customer spent $400 parts and labor for this upgrade).

Note: you can purchase Mundorf caps at


Images of Mundorf 1uf Caps in NM24

mundoerf mundorf


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