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The biggest problem is that the online services are offering upsampled files that are not reduced in amplitude. These have baked-in distortion. Yes, you can upsample without adding distortion, but you must take a 3 dB cut in level and this must be done before any fixed-point processing or...

Absolutely a bad idea!!!! DON'T Upsample Your Music Files! I cant emphasize this enough! Don't do it! Don't do it! Don't do it! Fixed-point upsampling will create distortion whenever an intersample peak exceeding 0 dBFS occurs. This distortion is often audible because it is quite severe when...

The balanced attenuator/gain stage allows a variable gain differential amplifier which optimizes the SNR over a wide range of gain and attenuation settings. All of the stepped attenuator topologies work well at unity gain, but many start to add excessive noise and/or distortion when the gain...

So, there was an AKM K120 DYN introduced in 1949 and there was an AKM K120 introduced in 1974. The only similarity is the name and AKM brand.

Is the "AKG K120" the correct model number? When looking it up, I found this: "AKG introduced its first headphone, the K120 DYN, in 1949." Did AKG reuse the old model number, or is it typed incorrectly in your post?

Thanks for catching this error! The page has now been corrected to reflect Sennheiser's published specification (102.0 at 1 Vrms). This removes the HD 800 S from our list of headphones that could be driven somewhat "safely" by the AHB2. The AHB2 could easily let the smoke out of the HD 800 S. We...

The output voltage limitation was due to the HE adapter. The adapter is a voltage divider. It attenuates the signal. The Topping was tested without the adapter, but the AHB2 was tested with the adapter. The AHB2 actually puts out quite a bit more voltage, but the HE adapter was attenuating the...

You are correct, many amplifiers would be unhappy driving the Susvaras directly. In contrast, the Benchmark AHB2 is perfectly happy with no load, a high impedance load, or a very low impedance load. For this reason, the AHB2 does not need the HE adapter when driving the Susvaras. We do not...

There is no need to use the HE adapter with the AHB2. If I understand you correctly, the HE adapter was used with the AHB2, but not with the Topping A90. The low output from the AHB2 was due to the adapter and not the amplifier. We recommend this cable (direct connection with no resistors) when...

This result is entirely incorrect. There is a major error in these measurements! The AHB2 delivers 80 Vpp on each output in stereo mode (single AHB2) and 160 Vpp in mono mode (using two AHB2 amplifiers). In contrast, the Topping A90 only delivers 49 Vpp. If you do the math, the output voltage...

Thanks for the feedback. We are out of buttons on the Benchmark remote control, but we may be able to add codes that are not on the control. This may be helpful: You can disable unused inputs and you can set inputs to a fixed volume. Or, you may be able to do this: If you select the DAC ON...

One HPA4 feature that is often overlooked it the fact that it uses a 256-step fully-balanced relay-controlled attenuator to adjust the output volume. The result is that the measured performance is available at a wide range of volume settings, not just where the volume control is maxed out (as it...

With these cables you can hide your money under the carpet instead of under the mattress.

Great question, here is the answer: We have a large number of professional customers that need simultaneous outputs. They need to be able to monitor with headphones without interrupting the line-level feed. We chose to make one product that would work for pro and hi-fi customers. As for the...

The HPA4 has one very special feature that is not found on any of the other headphone amplifiers. This feature is the 256-step fully-balanced relay-switched volume control. There are actually two of these in the HPA4 - one stereo pair for the headphone amp and one stereo pair for the line...

The AHB2 has a 3-position input sensitivity switch. In low gain (switch down), it requires 22 dBu (9.75 Vrms) to reach full output power. In the middle position it requires 4 Vrms (14.2 dBu) to reach full output. In the top position it requires just 2 Vrms to reach full output. The 22 dBu...

Amir: I can't blame you for not wanting to waste your time on cable tests. For the most part, the differences between cables are too small to matter (unless the cables are unusually long, or are subjected to high levels of electro-magnetic interference). Furthermore, the differences between...

It is important to place a low-impedance load, such as a 4-Ohm load resistor, on the end of the speaker cable. This will reveal the high-frequency attenuation that can be caused by excessive cable inductance. If the center-to-center spacing of the cable conductors is large, the cable inductance...

I have just created a blog where I am posting my research on ChatGPT as a writing tool. This blog allows the posting of comments, and I would encourage your participation if you have interest in this topic. https://benchmarkmedia.com/blogs/chatgpt-as-a-writing-tool

Here is an example that demonstrates the social engineering that is built into ChatGPT. Look at the two requests below, and look at the two responses. Clearly, I bumped into a social boundary with my first request. But, it accepted my second request, but ended the story with the Tube Amp and...