Audiophile Style: 5 stars for MU1 

Audiophile Style is a very active high end audio forum and it also features regular reviews by its founder Chris Connaker. Inspired by the many enthusiastic MU1 users on his forum pages, Chris did a review of the MU1 and concluded that it is a great sounding ‘set and forget’ unit and clearly the right product for 99% of the users. The remaining 1% loves to explore all permutations and combinations that a systems offers and Chris is certainly member of that group. He takes the deep dive and discovers that the MU1 is also well suited for that purpose:

“Grimm needed to get the audio from the NUC to its own FPGA, which appears as a sound card/device to Roon, before it was output to a DAC. Rather than any of the common methods of doing this, such as I2S or USB (routed internally), Grimm wrote its own DMA controller. Grimm uses the PCIe interface for transferring audio between the FPGA and the NUC/motherboard, for extremely fast and stable communication. This is not a trivial task, and is well beyond the skill set of almost every audio company. 


Listening to Chris Isaak’s cover of Only The Lonely, made this very apparent. Isaak’s voice sounded silky smooth, and sucked me right in. The acoustic guitar was lush, with a wide soundstage, neither of which Roon’s upsampling could match. Staying with acoustic music, I played Dave Matthews Live at Luther College. On Christmas Song, the 4fs oversampling gave the acoustic guitars a much fuller body and silky sonic texture when played through the EMM Labs DV2 DAC, and to a lesser degree through the T+A DAC 200 using the BEZ 2 pure Bezier interpolator. Based on my many hours of listening through and experimenting with the MU1, I believe it sounds best set to 4fs oversampling while playing acoustic music. This is its sweet spot. 


The Grimm Audio MU1 digital music source is absolutely the right product for many listeners in our wonderful hobby. If perusing the MU1 thread here on Audiophile Style is any indication, most people set it and forget it, at either 2fs or 4fs oversampling. The concept and validity of an external up/oversampling device has long been proven highly effective in many audio systems. The MU1 takes this a step further by including a Roon core and an advanced FPGA working to extend the capabilities of Roon, to deliver a pristine audio signal out to a DAC. “ 

The beauty of an online audio forum is that users of the products can add their personal experience to a review and the MU1 on Audiophile Style is no exception. The comment section below the review is therefore a wonderful extension of the article. 

Read about MU1 >

“The future for the MU1 looks very bright.”

Chris Connaker, Audiophile Style
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