Gustard H20 Opamp Dual LM49720 Full Balanced Class A Headphone Amplifier Pre Amplifier

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Price: $929.00
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Each channel uses two independent amplifying units to form a symmetrical output line, Single-ended and balanced output are at the same time ;

The front class consists of a single 4-way amplifier circuit, using two LM49720 dual op amp;
Have a separate pre-stage output, can be connected to active speakers or pure after the class;
The use of matrix relay volume, effective to ensure that 4-way volume unanimous;
Native full-balanced architecture, from input to volume control to before and after zoom, without any conversion, complete four-way architecture;

Technical Parameters: 
The power amplifier circuit uses separate Class A lines, each channel 2 pairs of power tube, a total of 8 pairs of power tube; 
The main filter uses Nikon nichicon audio capacitor KG gold tune 
Equipped with third gear gain (high,middle,low), Support amp and line (XLR) output at the same time; 
There are three inputs: RCA * 1, XLR * 2 
The left and right channels each adopt a custom 50W audio ring transformer, completely independent of each other without interference; 
All aluminum chassis, silver and black colors available;

Machine size: 330 * 260 * 65MM (without protruding parts); 
Packaging size: 420 *360*175MM;
Package weight: 6.0KG;

H20 Parameters:
Line input: 1*RCA, 2*XLR
Line output: XLR * 1 (Preamp output)
Amp output: 1*6.35mm single-ended high resistance,
                     1*6.35mm single-ended low resistance
                     2*Three-core balanced Output, 1*four-core balance output

Analog input:
RCA standard input group, input sensitivity typical value: 2Vrms; input impedance 47kΩ
XLR balanced input two groups, input sensitivity typical: 6Vrms; input impedance 2.4kΩ
Front analog output (XLR):
Output impedance 200Ω
Frequency response: 20-80kHz /-0.1dB
Signal to noise ratio:> 122dB
Channel crosstalk: -130dB @ 1kHz
THD + N: <0.0004%
IMD: <0.0004%

amp output:
Frequency response: 20-80kHz /-0.1dB
Signal to noise ratio:> 120dB
Channel crosstalk: -120dB @ 1kHz
THD + N: <0.0005% @ 6000mW into 32Ω LOAD
IMD: <0.0005% @ 6000mW into 32Ω LOAD
Maximum distortion output power 6000mW into 32Ω LOAD
Maximum output power 12000mW @ 32Ω (THD = 1%)
Load power:
64Ω 5360mW
150Ω 2680mW
300Ω 1340mW
600Ω 670mW 

Shipping Fees

Worldwide Free Shipping on SHENZHENAUDIO, Please allow 1-3 business days for conduct Quality Control in order to ensure the products quality.

If a customer would like the order reshipped, they’ll be charged a reshipment fee. Customers may also be subject to a restocking fee of up to 20 percent of the product cost.

Which Couriers To Use?

Given the amount of shipping partners we work with and the vast coverage area we serve, there are likely regions with much longer transit times than others. If you have any feedback, suggestions, or problems with the courier of your shipment, please feel free to submit a support ticket via the "Contact Us" button below.

Our goal is to provide our customers with the best shipping experience possible at a reasonable cost. This is why we constantly negotiate with existing shipping partners for lower rates and actively test new couriers for potential opportunities.

PO boxes or APO/FPO

The ability to ship to PO boxes or an APO/FPO address depends on the item's weight. If an item weighs more than 9 pounds, we won’t be able to ship to these addresses because of our current courier agreements.

To determine if your order is eligible for shipment to PO boxes or an APO/FPO address, please contact SHENZHENAUDIO Support.

Estimated Delivery Time

For customers in the continental United States:
5 to 14 business days from the date of shipping

For customers in Hawaii and Puerto Rico:
2 to 4 weeks from the date of shipping
International customers can expect longer shipping times, depending on the country in which they live:

Canada: 1 to 3 weeks from the date of shipping
Australia, New Zealand, Germany, France, and the UK: 2 to 4 weeks from the date of shipping
Other countries not listed above: 3 to 6 weeks from the date of shipping

Please keep in mind that these are rough estimates and shipments can be delayed due to unforeseen circumstances, like postal strikes or severe weather.

If, for some reason, you don’t receive your order within the estimated time frame provided above and suspect that it might be lost in transit, please submit a support ticket from your transactions page and we can look into the order with the courier. Lost-in-transit requests must be submitted to SHENZHENAUDIO Support within 4 months of the date of shipping or before the courier archives the tracking information.

Easy 30-Day Return Policy

If you are dissatisfied with your purchase for any reason, you may return it to SHENZHENAUDIO within 30 days of the received date, subject to the conditions and exclusions below.

Eligibility Conditions

Please read conditions below. If all conditions are not met, SHENZHENAUDIO reserves the right to refuse the return. All returned items must be in new condition, in their original unaltered box (including an intact UPC code) and must include all packing material, blank warranty cards, manuals and accessories. SHENZHENAUDIO can only refund the original purchase price. Shipping and handling fees are nonrefundable.

Defective or Damaged Items

Defective items may be repaired, exchanged or refunded at our discretion for the same model or manufacturer's equivalent model.


Depending on where you live, the time it may take for your exchanged product to reach you, may vary. Please allow 3-5 business days for mail-in exchanges to be processed.

Refunds & Credits

Once we receive and inspect your item(s), we will credit your account. Please allow 5-7 days for a credit to appear on your account. In most cases, we will issue your refund in the same way you made the original purchase. Please note: we can only refund the original purchase price. Shipping and handling fees are nonrefundable.

You will be responsible for paying for your own shipping costs for returning your item. Shipping costs are non-refundable. If you receive a refund, the cost of return shipping will be deducted from your refund.


To return your product, you should mail your product to: 4F 405, Building F, No.2 Shangxue Science and Technology North, Bantian Street, Longgang Dist, ShenZhen, 518129 Guangdong, China

If you’ve done all of this and you still have not received your refund yet, please contact us at