New MU1 firmware v1.5.0

We love to introduce you to the new MU1 V1.5.0 firmware. Over six months of work went into this release. A lot of improvements were done ‘under the hood’, preparing for a feature rich release mid 2023. But we also added some highly-requested functions, the beta testers loved it.

All new functions can be found in the GRUI, the MU1 web interface we added with V1.4.0. The most eye catching ones are in the source selection. For instance, unused inputs can now be disabled in the user interface, so source selection with the MU1 dial is a breeze. Even better, you can rename inputs to present the name of your source, such as ‘CD player’ which will then be shown both on the MU1 display and the GRUI. 

Another welcome new feature is to set a volume offset for each input, up to +/-20dB. The MU1 will apply this offset when switching between two inputs. For instance, some Toslink connected AV receivers have loudness normalization to very low levels like -31 LUFS. If the playback volume was adjusted for this level, you were in for an unpleasant surprise when dialing back to the Roon streamer. The new default offset solves this. Along a similar line, it is now possible to adjust the startup volume of the MU1 between -63 and -20dB (it used to be fixed at -20 dB).

Many customers will appreciate the new option to toggle between two digital outputs. In the GRUI you select which output is your ‘second output’, which will be muted in normal use. When you double tap the main button (or click Second Out in the GRUI) the second output becomes active and all other outputs are muted. This comes in handy for customers with a dedicated headphone DAC who like to switch between their loudspeaker system and listening to headphones. But we’re sure you will find other nice uses for this feature. 

A few more nice additions: the MU1 can be put in stand-by from the GRUI; you can program the IR remote via the GRUI in stead of just via the MU1 menu system; the GRUI sliders have + and – buttons for more convenient operation; and in the MU1 setup you can check the disk size and free space of the internal music SSD. Everything is described in the new MU1 software manual

As said, most changes were done ‘under the hood’, improving the stability of the system. Large parts of the system code have been rewritten with new insights, such as the handling of the main button and the stand-by processor. The control software has become better in handling exceptions and offers extended logs in case a crash does occur. Last but not least, this update brings many improvements to prepare for the next big update that will make the MU1 an official Roon End Point and adds more streaming options. 

Regrettably there is also unfortunate news to tell. Our intention was to enable the built-in FM tuner of the MU1 with this release. A lot of work went into optimizing its soft- and hardware, but in the end we had to accept that the FM tuner in the MU1 would not be able to perform at a sound quality level worthy of the name Grimm Audio. Internet stations kept offering a better performance. So with a heavy heart we parted from one of the most cheerful, but also anachronic features of our MU1 concept.

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