Drop + SMSL HO150X

I just got the Drop SMSL HO150x this week, and have a ton of others to compare it to. It's basically an SMSL SP200 but with a quiet noise floor and smoother volume wheel. It doesn't get hot (lukewarm at best) and sounds flawless with lots of power and simple controls. I've got an SMSL C200 and DL200 as a DAC for testing, and the quality on the HO150x is noticeably better sounding than the onboard amplifier on either combo unit. I test for channel matching, and even though that varies per unit, this one is within .5db in high gain and tightens up after 30 percent volume. In low and medium gain matching is exceptional, within .1-.2db which is up there with the best analog amplifiers (my Topping A90's are always within .1db up to 20 percent then match by comparison).



The best part is the noise floor, really quiet in low gain for IEMs which the SP200 wasn't good for (on ASR it did lousy in the 50mv test). They really fixed all the issues and I'd be happy to use this every day. There's a DO400 combo here also I've been using all week, and could not tell the difference between them. The one downside is the size, it's wide and not that long, so plan your DAC choice so it has something to sit on in a stable way. If you have room to run side by side, the Topping D10b I have sits happily next to it (and the display matches the power button orange). This combo really adds up for me personally, since it has no MQA, remote, or Bluetooth antenna, just simplicity. If you've heard the JDS Atom, Magni Heresy, Drop THX One, or Topping L50 then you know what it sounds like already. It's complete transparency and a silent noise floor with nothing to get in the way.

I'm in low gain on the Hifiman HE5xx and can go as loud as I feel safe, and medium gain only if I'm equalizing with a preamp reduction. Most people aren't going to use high gain on this and get the best performance in medium. I might just keep the SMSL DL200 and sit this on top of it since it would cover all the different connectors. I'll over to send it to ASR to see if Asmirm wants to do measurements on this unit. I'm really confident this will do great under testing. If it's got the connections you need, then go for it. The same power on both headphone jacks, and I just use a Youkamoo 4.4mm to XLR adapter I had anyway if needed.

If you already have a 120 SINAD scoring amplifier, don't expect anything different. If you like the SP200 but the noise floor was too loud or scratchy volume wheel, you're going to love this because it's the "fixed" version with none of the problems of the SP200. The competition in this price range is the Topping L50, JDS Atom 2, and Schiit Magnius, both in price and performance. Without considering price, what is a clear upgrade? I have a Topping A70Pro and with the D70Pro Octo it's audibly better at a cost. The SMSL SP400/M400 combo I've got it also clearly superior. Short of those, even the Topping A90 or A90D Ive got isn't a clear upgrade from an audible perspective. In a blind, volume matched test I wouldn't be able to tell which it was vs. the A90's.
Grab one and sit an SMSL D-6s 5 volt DAC next to it and never regret it. Even a Topping D10b is transparent, and no remotes to keep track of or manuals to read. This one is in my category of equipment I'd recommend to anyone if it's got the connectivity you need. I had an SP200 for years and this has every shortcoming it had fixed while retaining all of it's power. It proves you don't need a remote control and IPS display to get top tier performance without melting down a credit card.

The Drop + SMSL HO150X is the successor of the venerable Drop THX AAA 789 achromatic headphone amplifier.

This time Drop have partnered with SMSL engineers who took the output power of the brand’s highly regarded HO200 amplifier and fit it into the smaller HO100 form factor. They also made sure to add several requested features, including balanced inputs and outputs, a dedicated preamp circuit for active speakers, and an intuitive three-position gain switch. The final product is the Drop + SMSL HO150X linear amplifier.

The Drop + SMSL HO150X headphone amplifier is a compact sized device yet it includes balanced XLR and RCA inputs, RCA preamplifier output and two headphone outputs, 4-pin XLR and 6.35mm single ended. The balanced output is for convenience only since the amplifier is not really balanced.

This is a well made device with full aluminium chassis and volume knob, smooth black finish and high quality switches expect for the plastic power button.

The amplifier output power is 6W/16Ω, 3W/32Ω, 550mW/300Ω, pretty impressive for the size and certainly enough to drive any pair of headphones. Noise floor is absolutely inaudible and the low gain setting allows for easy use with sensitive earphones.

The sound performance is exactly as advertised, a wire with gain. Linear, crystal clear and transparent, this is an achromatic amplifier that will not add or subtract anything.

Fast, dynamic and impactful but lean and dry on the low-end. Crystal clear and resolving mid-range without much harmonic variety but still not artificial or sterile. Sharp and airy treble with plenty of luminosity and a touch of brightness, it never sounds harsh or piercing. Open sounding and expanded with accurate imaging but not too deep or holographic soundstage.

This is the kind of amplifier that you can pair with all sources and headpnoes since it doesn't have a character of its own and shines with its absence.

If you need a powerful headphone amplifier with excellent measurements and masterclass transparency then look no further. The Drop + SMSL HO150X is the answer to your needs at a very affordable price.