...Not likely to cause a conflict. In general, in your computer you must select which device is doing the input of audio, and which the output of audio, on a per program basis. If something is ‘bus powered’, it is always best to verify, through specifications, what it requires and be sure it is getting what it needs to run. The thing is to know for sure, don’t assume that because it lights up, that it is getting the power it needs to run properly. Once your device is ‘happy’, there’s not much to worry about in terms of conflict.

In general, you want to avoid Hubs where possible. The MODX, if you are going to use its audio interface, should be connected directly to the computer’s USB port (not via a hub). If you wish to use a different device as your audio interface, the MODX can remain connected via USB, you would simply select the other device as your audio interface with the software application. The MODX can remain connected to the computer via USB for MIDI communication.

Your other concerns are ground noise. This can occur in any setup - because it is the caused by interconnecting multiple devices. But other than that, computers are fairly decent in letting you decide what you want to use. Get comfortable with configuring your devices - it is worth the effort to get comfortable with connecting and making the computer ‘happy’. Consider that it wants to know what you want to be the INPUT/OUTPUT device for audio. You are not using the built-in stuff... so you can expect to tell it what you want. Therefore, it’s the user’s responsibility to tell it what to do.

Each audio interface device will have a recommended setup... the MODX requires the installation of a low latency Audio/MIDI Driver (Yamaha Steinberg USB Driver), to get the best results. It is also ‘class compliant’ - which means it is able to work without a driver, but if you’re doing this seriously, you’ll want to get the recommended driver.

Make sure you read the instructions and follow the recommendations of the other external Audio interface.
The device selected as you computer’s Audio Interface, is the device that will connect to your monitor speakers... all other sources connect to the audio interface. The Audi interfaces merges all inputs going to the computer... and takes the audio from the computer and sends it to the monitor speakers.

Extra Credit:
“Minimum requirement” is the least you can do to get it to work
“Recommended requirement” should be your minimum... if you ever attend a trade show or manufacturer presentation, on any computer related stuff... pay attention to what the presenter uses. Notice it is never minimum requirement, just sayin’

The problem with hubs is they are an unknown and vary greatly in form and function. You are sending 14 audio channels, and the equivalent of 6 MIDI cables worth of data between the MODX and the computer, the hub doesn’t necessarily intelligently handle this. I just mention this as advice. Things like your mouse, QWERTY keyboard, etc, can utilize hubs, no problems... a momentary interruption in signal to your mouse is overcome without even noticing, lose one slice of music information, it’s catastrophic.

The concept of putting a mixer between your instrument and your monitor speakers is as much for flexibility as it is for an extra layer of protection from unexpected blasts of signal.
A direct box will typically convert signal
A mixer adds input buffering, some times EQ, some times Effects or options to feed Effects, in addition they can offer the ability to add additional input devices, some even provide +48 V phantom power for condenser mics...

While it is fine to plug your synth into today’s Monitors (like HS - Home Studio) they’re built to expect direct connection from keyboards... but a mixer is just that next step in building a more flexible rig. You want one that is able to do the job... the better the mixer the more likely you are able to use it to enhance your sound as well as expand your options

In today’s pro stage rigs, you often find the keyboard player has their own mixer which feeds their own stereo floor monitors and has a separate balanced stereo out to the Front-of-House. In the Home Studio, its mainly the flexibility and insurance against overload.

Thanks BM.

OK - so given the USB powering of my separate audio interface should not give rise to any conflicts, I am just wondering if the separate audio interface can do the job of buffering, or providing that extra insurance for my monitors, as a mixer would do?

The technical specs give me the following:

Instrument Input

Type ¼"
TS Female Unbalanced Input Impedance 0.5 MΩ

Line Outputs

Type ¼"
Balanced Output Impedance 51Ω

Not a strictly MODX question, but hoping this is an easy question ...

When I mentioned “specs”, you want to be sure a “bus-powered” device is plugged into a USB port where it receives the voltage and current it requires. For example, if you want to bus-power something using a MONTAGE or MODX, you will discover the “To Device” port on the synths is rated at 5V/500mA... that means do not use this as a power source for a device that needs more than 5V, and draws more than a maximum of 500mA.

Most people know to match the Voltage, but don’t know about the amperage (current). Plugging in a device that needs 1A (amp) to run, would be bad... amperage is the current... a device will not draw more current than it needs, but trouble happens when it can’t get enough to run properly. So while you want to match the voltage requirement, as long as the connected device can draw the current it needs, you’ll be in good shape. So in this example 500mA or less.

This is one reason why plugging a bunch of stuff into a hub can be if-y...

When a device cannot draw enough current things heat up and will eventually burn out (damage can occur).

I cannot comment on your specific device, (and those are not the specs that are important in the bus powered situation... but virtually any mixer you place between your source and your speakers acts as a buffer...

Recognize that the Studio Monitors have an “Input Sensitivity” knob — civilians think it is a Volume knob (probably because it does effect the volume)... but, here’s what you need to know: it is the Input Sensitivity setting used to match monitor speaker’s amplifier to the signal strength of the source. “How much” help does that signal need. Volume Knobs go from 0-10 (or 11 if you’re in ‘Spinal Tap’... ). This looks reversed...

For example, you may see a scale on the Knob that shows a values from “MIN” (minimum), clockwise to +4dB when straight up at 12 o'clock, and -10dB as the maximum. When you have a consumer level product (like a handheld tape recorder) you need the amplifier in the monitor to boost and help that weaker signal — the minus ten (-10dB) setting is used to match the monitor speaker’s amp to that lower level INPUT.

+4dB is used when the input source has more Output level, therefore it needs less help from the monitor speaker’s amplifier.

So the weakest input signal that you can plug into these HS Monitors is a device that outputs at least -10dB
The more powerful the source, the less help it needs from the built-in amplifier.

You cannot, for example, plug a microphone (-50dB), nor a guitar (-35dB) directly into these monitors and expect anything like good results... the Input Sensitivity does not match signals that weak.

Now, again, that said... yes, you can, technically speaking, plug your keyboard directly into these monitor speakers... the synth typically outputs +0dB or +6dB (although can be set to -6dB or +12dB when required). The role of a mixer is to prepare signals for your speaker system.

Simply putting a mixer in line between signal source (your instrument) and destination (the monitor speakers) makes it a buffer.

Real World Humor added to drive home the point...
Imagine you plug a microphone into the MODX to setup the Vocoder. Many first timer Vocoder users, not knowing exactly how to set it up, often turn everything up to maximum — while trying to get the sound dialed in, they can’t hear it, they think it must be working - it’s just not loud enough!

Well typically, it’s usually a switch they forgot to activate, so that when it does come on, it comes flying out of the speakers at ear-splitting volume. With so much high frequency content... some tweeters don’t survive the onslaught.

The experienced user, with a mixer in between, has been here, done this, and has a set of blown tweeters hanging on the studio wall to remind them of this very incident... now they have a mixer and understanding signal flow, they can turn the mixer’s main output down... (completely protecting the speakers)... now with metering on the mixer they can SEE when the signal is flowing... the peak overload lamp takes all the ‘abuse’ (it likes it, it doesn’t get to glow unless you’re dangerously close to clipping) it loves to take the HIT instead of your expensive monitors and your more valuable ears.

Some mixers have both input and output metering, some have a peak overload lamp (on the input) with a meter on the output, etc.
What you use, and come to count on the mixer for, is to assist you preparing signal for your monitor speakers (treat them as if they are as valuable as your ears).

Thanks for the question, and my apologies if you know all of this about Input Sensitivity, et al... but we have so many readers that have similar questions about getting a mixer. Eventually, you’ll want to get a mixer.