If you are hearing noticeable (i.e. about 5 feet away from the speaker) noise, the first step is to determine the source of the noise. The high-frequency noise and grounding flaws created by custom modifications or aging upstream components such as a CD player, D/A converter, or preamplifier may be audible as a loud hissing or buzzing noise. Typically humming noise is the result of grounding problem and hissing noise is caused by switching noise from external device (most likely from computer or its power supply). The first step is to start by disconnecting source devices one at a time until the noise disappears.Sometimes section of an old home might not have proper AC ground and the noise is coming from other household appliances. If you are unable to determine the source of the noise within the chain of audio components, and the noise can be heard by simply connecting the power amp and the speaker (without any upstream components), try other power outlets in the house and always use a quality power strip with noise filter.

Even if the source of the noise has been found, removing it is a challenge. Below are some common cases:

1. Computer switching noise passing through USB cable – the noise could be coming from the USB cable shield or ground pin. Try to use a powered USB hub and quality USB cable. There are high-end USB noise isolation devices but keep in mind that a cheaper solution might be to upgrade your computer.
2. Grounding conflict between components – this can be caused by poorly or incorrectly designed ground wiring that allowed noise from one component to affect another through the common ground in the system. Therefore a simple solution is to “cut off” or isolate the ground of the offending component from other parts of the system. This can be accomplished by using a “cheater plug” – an AC ground lifter or three-prong/two-prong adapter.  
3. If the ground loop noise is caused by cable TV set-top-box, a ground loop isolator such as the Viewsonics VSIS-EU Cable TV Ground Loop Isolator (available on amazon.com)

For 110V AC, we recommend Tripp Lite Isobar power strip.

Use energy saving power strip such as “Tripp Lite 8 Outlet Eco-Surge Protector Power Strip” where turning on the master device will turn on all the source devices. Tripp Lite power strip also comes with good noise filter. Another type of power strip such as “Belkin 8-Outlet Conserve Switch Surge Protector with 4-Foot Cord and Remote” is also highly rated by consumers.

The following fuses are used in our products:

MCH-K38    T10A
IDA-16       T7A
IDA-8        T3A
STA-9        T3A
DAC-9       T1A
HPA-9       T1A
ST-10        T5A
DAC-10     T2.5A
REF-20     T5A

All the fuses have the same size: 5x20mm

There is two side to a coin. An entry level amp has 200W@4 Ohms and 100W@ 8 Ohms. But why not design an amp that also raise the performance and power with 200W@ 8 Ohms?  This is exactly what NuPrime does with amps design.

Another fact is that NuPrime’s amps are capable of more power than the spec suggested. So if 4 and 8 Ohms are specified at 100Wx2, that means the power supply is a 200W PSU. And we are extremely conservative about our power rating (we provide conservative RMS rating, not peak power). A customer reported 180W for IDA-8 because he is using just one channel to do the measurement. So, if IDA-8 is in a bigger case, and we put in a 300W PSU, you will see a higher rating. In reality, you get more than 100W per channel from the 200W PSU, because not both channels are driven at the same time.

Why don’t we put in a bigger PSU? Each model is designed for specific product position and adding more power will certainly increase the cost and size of the product.

LPS-205 – any device that can be powered by 5V/2A. This includes Omnia Stream Mini, Stream Mini DAC, Omnia WR-1, Omnia SW-8.

LPS-212 – any device that can be powered by 12V/2A or 12V/A. This includes CDT-9, Omnia S1.

The GND pin of the AC Inlet is connected to the common ground of the chassis.

They are as shown in the photo. N for neutral, L for live.