It has been a while since I sat down to write some impressions her at Head Fi, however the opportunity presented itself and herein are my thoughts. Thanks for reading.
I have had the Slimline UHA-4 unit in my possession for about two months. It has been used as both a USB DAC/Amp combo and a portable amp. In summary I like how this unit sounds and that it is such a compact performer.
The USB was recognized right away by computers running MAC OS 10.6.6, Windows XP, and Windows 7. This unit is charged via the included USB cable which also functions to “feed” the digital files. With the advent of home/car chargers that allow charging using the USB plug format the charging of the UHA-4 should provided added versatility.
The one feature I wish was incorporated is a line out, this would allow the user to feed the decoded digital files to an external amp of the users choice. I realize this feature is of minimal use to most users since the intended market is for those looking for an DAC/Amp unit with a reduced footprint to be used on the go.
Barring this small issue the UHA-4 sports some cool features, the main one being its small size. This is followed by low/high gain switch, x-feed, and an Alps digital volume control. The width of the UHA-4 allows it to sit below an iPod Classic or an iPhone perfectly, thus adding to its usability.
The unit sports two LED’s, the front is the power indicator and it is green if the battery has at least 1 hour of remaining running time. This turns red when the remaining running time is less than 1 hour. There is a 2nd LED on the back by the USB port, this turns orange while charging. A nice feature is the use of a 500 mAh iPod battery, thus it would be an easy task to find a suitable replacement.
Your can read more about this unit at: http://www.leckertonaudio.com/products/uha-4/ For those interested the technical specifications are:
• Dynamic range: 108 dB A-weighted with analog input (100 Ω load), 93 dB A-weighted with USB input
- Up to 40mW into 32Ω,<1.0%TH
- Up to 50mW into 100Ω,<1.0%TH
- Up to 15 mW into 300Ω,<1.0%THD
- THD, A-wtd: <0.025%, 1 mW into 32 Ω
- 10 dBV max output level into high-impedance load (>600 Ohms)
- Frequency response: 13 Hz to 22.5 kHz, +/- 1dB
- Dimensions: 3.3" x 2.75" x 0.47"
- 24 hours typical runtime on full battery • 32kHz, 44.1kHz, and 48kHz sample rates supported for USB audio streaming (16-bit)
- Enclosure: extruded aluminum, anodized
Below is a list of the cans I used with the UHA-4, all four were driven effortlessly and IMO the sound was engaging, detailed, and with very good extension. Actually the clarity was the most distinctive feature.
- Audio Technica ATH-ESW9
- Yuin OK-1
- Ultimate Ears TF10
- Westone 2
In closing I would like to thank Nick of Leckerton Audio for the opportunity to try the UHA-4.