av: Guide to IEMs, DACs, Preamps and Podcast Studios

Well, thanks to Lucas, I got some great advice about building up another Podcast Studio. I had previously built one at the start of the Pandemic and it has worked great, the core is a Rode NT-1A (which I famously mounted backwards), a Focusrite Scarlett 2×2, but in looking back at great headphones that I’ve had, I realized that I had done a bunch of things wrong:

  1. The Scarlett is actually not that great at being a Digital-to-Audio Converter (DAC) and it turns out there is a whole science to making sure that your headphones have enough voltage and don’t have distortion when they are overdriven. As an example the Sennheiser HD-650 is a high-impedance headphone and needs 8 volts plus to drive it to 120db (that is loud and clean). The MacBook for instance only support 3V at 150 ohms and above.
  2. I wanted to build another studio so that I could also do instrumentals. This has to be the most backward thing ever, I want to play an instrument so I can play with the gear. The Scarlett is nice, but it is a basic Microphone Amplifier so doesn’t have all these things.
  3. I wanted to take advantage of all this lossless audio that is now around with much higher bit rates and frequencies. The original world was pretty good, 16-bit audio and 44.1 KHz is pretty amazing, but Apple now supports lossless up to 24-bit and 192 KHz. I doubt my ears can hear that well, but might as well see it that’s possible.
  4. I was inspired by watching the ERAS tour to wonder what Taylor Swift was wearing as her In-Ear Monitors (IEMs) so why not see what the highest quality is.
  5. The Rode NT-1A is really nice, but I was wondering what the classic microphones are.

New Studio: SM-7B and Moonshot Variations

So with that being said, here is what I ordered and a review of each component for the new system

  1. Shure SM-7B. This is the classic microphone that Michael Jackson and many other performers have used. The latest SM-7B includes a built-in preamplifier as it is very low gain. So it has built-in 18dB and 28dB amplifiers with switches on the back. It also has built-in bass roll-off and mid-range boost. It also has an integrated pop filter and is very compact.
  2. Rode PSA-1A. I have the older PSA-1 and I have to say this is an incredible stand. The new PSA-1A is basically the same but it has a nice routing system for the microphone XLR cable. It includes both a desktop mount and also something for an in-hole system.
  3. Universal Audio Volt 2. I called Lucas and asked what should I get, well the older systems had a processor inside the analog to digital box, but the new Volt 2 doesn’t have that much and relies on the computer you are using. It also comes with a huge range of “free plugins” that are going to make your Digital Audio Workstation (DAW) amazing. As a Headphone output, its maximum output power of 32 Ohms is 84mW, 22mW into 300 ohms, and 12mW into 600 ohm. The traditional specification is measured at 1KHz and it gives you 0.001% distortion there at -1dBFS. This is quite a lot to calculate, but to review from our last post, Voltage is sqrt(P * R) so sqrt( 0.022*300) is 2.57V at 0.001% THD. Similarly, that means for a low impedance 30 ohm headphone that would be 1.63V.
  4. iBasso Audio DC06 Pro. To drive this, I needed some more power and looking at all the reviews, the iBasso is a tiny, you can clip it on your belt DAC and Amplifier with a USB C on one side and then both 3.5mm unbalanced and 4.4 balanced outputs. And an eye-popping 384KHz DAC. It has plenty of power to drive the Moondrop to ear splitting levels.
  5. Moondrop Variations. I wanted to try an In-Ear Monitor instead of big headphones. I went to Headphones.com, Headphonesty, Audiosolace, Audiophile On, Headfonics, Soundgearlab, Soundguys (I might still get the venerable Etymotic ER4XR or really go crazy with the THIEAudio Monarch MkII), Head-Fi and Crinnacle. Crinnacle has his own unique evaluation system and was raving about the Moondrop Variations which has no less than three different kinds of drivers which are affectionately called Tribrids. Others think it doesn’t sound that good, but I went to eBay and bought it and I have to say it is a big bulky IEM but I love it. The sound is just sublime. One thing I have to say is the move to standardized connectors, either 0.75, 0.78 or MMCX is really great, I have so many earphones where the wires have worn out and this is a nice fix. These things are very efficient to drive with 118dB/Vrms@1kHz with 15.2-ohm resistance. The stock tips are pretty nice and people like the Spinfit CP155 so I need to try those. This has for bass 10mm LCP Dynamic Driver, for mids dual Softears-D-Mid-B and for treble dual Sonion EST.

I also considered just getting another set of headphones, but the HD-650 is just so good, I really wanted to try IEMs. And I could have gotten an earbud, but again, I wanted to try a true IEM with a Bluetooth connection.

Listening to Lossless on Apple needs an external DAC

The main issue here is that Apple supports up to 24-bit/48KHz internally, but to go to the full 24-bit/192KHz requires an external DAC, so off to find them for all my setups.

So off to find some great DACs and deploy them against my Mac setups. There are both desktop only, but also if you don’t need a lot of voltage, there are lots of DAC/Amps as Headphonesty, AndyAudioVault (Youtube) and MajorHiFi covers including:

  1. iBasso DC06Pro. This is just $119 and supports up to 320mW at 32 ohms using the ES9219C quad DAC (this translates to . And it has some amazing bit rates up to 32-bit/384KHz. As math aside, since R=V/I and P=V*I, then given R and P, you can calculate the current I with R=30, P=0.32, then P = R * I^2 so I = sqrt(P/R) = 0.1A and then you can solve for V as V = R*I = R*sqrt(P/R)= 32*sqrt(0.32/32) = 32*0.1Amp = 3.2V. The complete specs from Headfonia are THD+N is 0.00013%, output is 3V at 32 ohms, 4V at 300 ohms for the 4.4 Balanced. For the 3.5 single, it is 0.00018% THD+N at 300 ohms and 2Vrms for 32 to 300 ohms
  2. Qudelix-5K Bluetooth DAC and Headphone Amp. OK, this is kind of a cool device in that it has a Bluetooth receiver too. It costs just $100 and like the iBasso has a balanced output at 4.4 which gives you more power. It has great specs and very low noise. It’s 300 ohm power is 23 mw and at 33 ohms it is 85mw. This gives it an output voltage of V = R * sqrt (P/R) of 2.63V at 300 ohms and 1.67V at 30 ohms for the balanced plug. The unbalanced 3.5mm, you get 52mW@50 ohms or 1.61V

Upgrading the Rode Setup with Schitt Magni+

One other thing I had to do was get a much better amplifier for the existing studio setup, so after looking at lots of different brands, I settled on the Schitt Magni 3 which for $199 has both a DAC and an amplifier. The main reason is that it provides an eyepoppting 8.8V @ 0.01%THD which is incredible. The Sennheiser HD640 needs 6.3V to work at that level given its impedance is 333 Ohms and it relatively insensitive at 104dB/mW at 1Khz.

I have to say the results are astounding. It is probably just bias, but the sound was really good and clean even at the highest levels. Overal the Schitt line is really good and it is nicely built like the Jotunheim

Upgrading the VC1000 with the Qudelix 5K

I was also thinking of getting my third setup up to quality. I’m currently using those old VSonic VC1000 and they sound pretty good. These are relatively efficient at 50 ohms and 105db/mW@1KH1, but that still means they need 5.6V to really work well.

Using the Moondrops as TWS on the go with littleWhite

I wanted to try what are called True Wireless Stereo Adaptors (TWS), but there are not that many available which aren’t noisy.

The last experiment was to take the Moondrops and try them with their littleWhite, which is Bluetooth 5.2 to 0.78-inch connectors. So you can unplug your Variations and have a “collar” system that gives you incredible quality.

The Moondrop littleWhite itself is a little hard to understand, but basically, you push the power button for 2 seconds to turn it on or for 5 seconds to force pairing and it works really nicely. It’s a great way to bring your very best IEMs on the road and not have to get a set of bulky headphones.

I tried to get the much smaller FiiO UTWS5 which are just little ear hooks, but they look like they are out of production. The iFi GO Blu seems noisy. The Shure True Wireless can work, but they are expensive and they use an MMCX connector so you have to adapt that to the .78 inch ones used on the Moondrops. Reddit has a host of these but many are not in production anymore like the KZ AZ09 or the TRN BT30.

Moondrops with Qudelix Bluetooth

OK, this is another variation, here you use the conventional wire and then clip it to a Qudelix-5K Bluetooth receiver, so you don’t have the necklace and have to manage the cable.

Upgrading AirPod Pro 2 with Foam Ear Tips

Well, I don’t mind the silicon ear tips on the AirPod Pro, they are easy to remove but they don’t isolate you that much. So I had tried foam earplugs, but then my older AirPod Pros died (I suggest the 2-year warranty addition for $29 and use your Amex card to get an additional year). But, Tom’s Guide convinced me to try again and they do isolate more and improve the bass, so these little foam things seem to help slightly. The Comply Foam Tips for $25 at Amazon fit the bill.

Updated chart of Amp to Headphone

Use the calculator at Headphonesty.com to calculate the Voltage needed and repeat the table from before. Note that the entries for Brainwavz and VSonic are correct, turns out that you can’t drive them to 120dB because they need way too much maximum power, so don’t use this for true concert work:

@1KHz (ohms)
@1KHz (db/mW)
Input Power (mW)
120dB P, V and I (RMS)
Sennheiser HD650333104500120mW, 6.31V, 18.95mA
Shure SRH4404111650061mW, 1.58V
Brainwavz B24011060250mW, 3.16V,
Vsonic VC10005010550632mW, 5.6V, 112mA
Moondrop Variations15118dB/Vrms
104mW, 1.25V, 83.6mA
Headphone Voltage needed

Now we reproduce that table of Amplifiers and needed voltages

Device (V required)Voltage@1KHz
(Vrms 0.01% THD)
Sennheiser HD650
(333, 6.3V)
Shure SRH440
(41, 1.6V)
Brainwavz B2 (40, 3.2V)Vsonic VC1000 (50, 5.6V)Moondrop Variations
(15, 1.25V)
MBP 2021+1.5V <150Ohm
3V >150Ohm
Schitt Magni8.832V
iPhone 6+0.933VXXXXX
Cozoy Astrapi0.7VXXXXX
HeadRoom BitHead1VXXXXX
Basso DC063.2V @ 32Ohm
Qudelix 5K1.67V@33Ohm
Device vs the DAC work

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