Drop + SMSL HO150X Review

In this review, we’re taking a look at the Drop + SMSL HO150X desktop amplifier, which costs $169 USD.


Disclaimer: Drop sent us the HO150X for this review. All thoughts and experiences with the product reflect my unaltered opinion.

S.M.S.L & Drop

SMSL, a Chinese audio company known for its wide range of value-driven products, consistently designs well-built, high-quality DACs and amplifiers. Founded in Shenzhen, China, in 2009, SMSL (ShuangMuSanlin Electronics Co. LTD) has a strong track record and has acquired many fans around the globe. My personal experience with their gear has been consistently positive, and today, we’ll explore their collaboration amplifier with Drop company.

Drop (formerly Massdrop) is an American e-commerce company headquartered in San Francisco, California, that stands apart with its focus on community-driven product development. Leveraging data and feedback from its passionate community, Drop curates and creates exceptional audio products and mechanical keyboards that cater directly to enthusiast interests. Beyond simply shopping, the Drop community offers a space for learning, discussion, and direct participation in product development through polls, discussions, and interest checks.

Drop + SMSL HO150X Desktop Amplifier

We are well accustomed to SMSL’s HO line-up, as my colleague take a close look at the HO100 and the HO200. Let me leave a small snippet from Haja (Nanotechnos) below.

Sound quality is outstanding, build quality is lofty, power is bottomless, and the conception design makes it the perfect desk companion, whether if paired with the SMSL DO100, another DAC, or even a DAP.

for the price, the SMSL HO200 is one, if not the best, solid-state headphone amplifier you could get at the moment. Build quality is great, the sound is superb, I/O is complete and either as a headphone amplifier or a pre-amplifier, the device was just darn impressive.

We reviewed a lot of gear from SMSL in the past on Headfonia, be sure to check them out!

Now that we’re familiar with the HO line, let’s dive into the HO150X – a collaboration between Drop and SMSL. As the name implies, this model bridges the gap between the HO100 and HO200. While the HO100 delivers 3W of power into a 16-ohm load, both the HO150X and HO200 double that power output to 6W. Like the rest of the HO line, the HO150X leverages a Precision Linear Feedback Circuit, enabling it to pack impressive power into its surprisingly compact form factor. It is substantially smaller than the HO200 while retaining the same power. It is also around 120 bucks cheaper than the HO200. Here are the specs and highlights.

  • Headphone outputs: XLR 4-pin, 6.35 mm unbalanced
  • Preamplifier outputs: RCA Unbalanced
  • Output power: 6,000mW (@ 16 ohms), 3,000mW (@ 32 ohms), 550mW (@ 300 ohms)
  • SNR: 134 dB
  • DNR: 134 dB
  • THD + N: -122 dB, 0.00007% (1 kHz, 32 ohms)
  • Output impedance: 0.1 ohms
  • Gain settings: Low (-12 dB), Mid (0 dB), High (+12 dB)
  • Dimensions: 5.9 x 5 x 1.5 in (15 x 12.8 x 3.9 cm)

Packaging & Accessories

The HO150X comes inside a medium-sized cardboard box featuring the amplifier’s outline artwork on the box. Drop + SMSL did not include any product details or specifications on the box and aimed for a cleaner, simpler look as usual. The unboxing experience is similar to the other SMSL products; the device and the accessories sit inside a foam compartment, safe from any damage that might come from the outside. The accessories are minimal; you get a 1.5m power cable, and that’s pretty much it. 

Design & Build Quality

The HO150X uses the same aluminum chassis as the HO100, with a matte black anodized finish and durable construction throughout. There are no assembly imperfections on my unit, as expected from SMSL. 

The HO150X is a very compact amp and will only take up a little space on your desk, which is, in my opinion, one of its selling points. This thing has so much power in such a small footprint; it’s wild how far the linear amplifiers come. It has a slightly different layout compared to the HO100, with the addition of a 4-pin XLR headphone output. Note that the balanced outputs are only there for convenience. There’s no performance difference between the ports. The HO150X has a retro-style power button with an orange LED inside, giving good tactile feedback when pressed. On the front, we have a couple of vintage lever-style switches along with a vintage power button and two headphone outputs. The amp’s design is simple yet elegant; however, I am not a big fan of the power button. I think it messes with the congruity of the overall theme.

The overall build quality is impressive, and the knob feels sturdy and provides good feedback. The inputs are located on the back of the unit, and surprisingly, it comes with a plethora of inputs and outputs for a 160-ish USD amplifier. Kudos to Drop and SMSL here. The quality of the connectors feels solid and well-assembled. No complaints here!


Drop & SMSL describe their first collaborative effort, the HO150X Linear Amplifier, as the next step in their ongoing pursuit of the perfect “wire-with-gain” experience. The partnership aims to leverage SMSL’s expertise in low-distortion amplification design, specifically the Precision Linear Feedback Circuit, which boasts incredibly low distortion levels of 0.00007%. This is not our first time seeing this design, though; SMSL has been acing every measurement out there for the past 1-to-2 years using this design. The HO150x offers a dedicated pre-amp circuit designed for active speakers. There’s a lever switch to swap between the inputs. However, the RCA pre-amp output and the headphone outputs are powered simultaneously.


The review continues on Page Two, after the click HERE or by using the jump below.

Page 1: Drop + SMSL, HO150X, Packaging & Accessories, Design & Build Quality, Features

Page 2: JDS Labs Atom 2 DAC & AMP Stack Performance, Pairings & Comparison, Last Words


4.4/5 - (231 votes)

Long time Tech Enthusiast, an ambitious petrol-head, Yagiz likes his gadgets and always finds new ways into the tinkerer's world. He tries to improve anything and everything he gets his hands onto. Loves an occasional shine on the rocks.

Be first to comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.