It's wonderful that Lotoo provided Asahi Kasei Microdevices (AKM)'s AK4499EQ zenith the time capsule needed to transport this legendary chip forward for the enjoyment of future audiophiles.
With Mjolnir built on Lotoo's LTOS custom user interface, this uber-flagship DAP adds its own value with a digital subsystem – consisting of Lotoo's tried-and-true NXP i.MX 6ULL and Analog Devices Blackfin DSP processor sub-system carrying proprietary code that generates clocking and audio data I2S for its AK4499EQ.
Marking Lotoo's return to current-output DACs for the first time since 2014 when Texas Instruments' (TI) PCM1792 appeared in Paw Gold, Mjolnir's four-channel AK4499EQ outputs analog to a current-to-voltage I/V stage where D/A conversion errors manifest as a DC offset that is easy to filter out – instead of more sinister total harmonic distortion.
The desire for purity is mirrored in Lotoo's construction of Mjolnir. Multi-layer PCBs and a 3mm thick metal locked-in shield for the audio circuit, down to individual screws fashioned from 304 and 316 stainless steel and a CNC chassis built to surpress quality-averse vibrations, are testament to Lotoo's attention to detail.
Mjolnir's pristine small signal gets fed to its power stage consisting of eight TI LME49600 buffers – the first and only time Head-Fi has seen these parts implemented in such a topology – making up an incredibly powerful paralleled quad-mono balanced output stage capable of 5 total watts.
With Mjolnir's 20 volt battery power rails running closer to each LME49600's power supply requirement, each op-amp already acts linearly in the open-loop before mandatory feedback is added. Dynamics are unhindered regardless of load complexity – undoubtedly bolstered by LME49600's incredible slew-rate spec.
The negative feedback finally applied as the cherry on the cake sees Mjolnir achieve up to an incredible 130dB dynamic range via 4.4mm or 4-pin XLR headphone outs, or 134dB via dual 3-pin XLR line-outs.
Indeed, Lotoo built Mjolnir to function perfectly as a DAC too, its Wi-Fi undergoing Roon testing and certification, with DLNA readiness meaning use with UPnP software is also possible. Digital outputs into your Hi-Fi system's DAC also sees Mjolnir execute transport duties via AES/EBU, S/PDIF RCA and optical.
So here is Lotoo with Mjolnir proudly asking whether your all-in-one system even hubs, building the ultimate all-in-one to end every argument against it. Check out Lotoo's other devices here, or view our other DAPs here.
DAC 1 X AKM AK4499EQ
Amp Paralleled quad-mono LME49600 op-amp output