iBasso AMP13

Nutubes return to iBasso Audio, bigger and better through Amp13 for DX340. The size and power supply afforded by their flagship music players allowed iBasso to take this tube design to new heights.

That extra circuit board space has allowed Korg's sixth-generation Nutube direct-heated triode to achieve new levels of signal-to-noise ratio, transparency and output power.

Holding its own even against its balanced Amp14 sibling, iBasso's Amp13 brings plenty of even-order harmonics to sweeten synergies given its single-ended operation throughout. Eschewing bridge-tied load operation means Amp13 also outperforms its counterpart into low impedances.

Headfonics confirm Amp13 does all the above, offering the liquidity tube lovers desire. Musicality won out for Audio-Ph. Upgrading to iBasso's mature Nutube tech was totally worth it to Audiophile-Heaven. [See Product Desc. For More]

Placed on Amp13's voltage gain stage where it will yield the biggest sonic difference, this Nutube's small output then gets boosted by a Toshiba FET buffer. This preserves Amp13's triode square law, and grants it enough juice to drive the rest of the solid-state output stage. 

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iBasso built Amp13 with dual 3.5mm outputs. The hybrid Nutube section directly feeds Amp13's low noise, low output port (2.5Vrms) for sensitive IEMs.

Meanwhile, an intermediary solid-state driver stage gets added for the high output port (4.1Vrms) to push Focals and Fostexs needing more gain.

DX340's dynamic range spec is maintained through NJR's NJU72315 digitally-controlled analog volume part, and iBasso hide yet another trick up their sleeve: forcibly driving the ground signal of Amp13 to increase output power and reduce noise.

The separate 2,000mAh analog battery aboard the DX3XX line supplies the backbone of power for Amp13's high operating voltages, with four clean, individual DC power sections for crucial parts of the module.

The anode packs 21 volts of supply, while eight volt output rails continue to maintain excellent open-loop linearity before negative feedback.

Such is expected of a high-performance iBasso Amp13 module that yields excellent distortion and noise specifications, while capturing the romance of tubes in DX340. Also view Amp12 here, all of iBasso's other portables here, and our music player catalogue here.