Audio Engine P2.
I’ve had a few pair of speakers that worked well in a nearfield desktop system, The NHT SuperZero 2.1 and Paradigm Atom are good choices. Haven’t heard them but the new Sony SSCS5 3-Way 3-Driver has received rave reviews and they’re on sale for half price now on Amazon, $88. Adding a subwoofer under the desk helps any speaker of that kind work much better, the NHT sub is what I've used but I'm sure there are other inexpensive ones that would work.
Decware makes some mini desktop radials that are impressive if your setup allows. I use them in a setup at the office and they are the best minis for bass I have ever owned. Even at low volumes you can feel the base at the keyboard - I forget sometimes and they can startle me when typing. They are passive while I believe most desktop speakers are active. At home, with a more limited space on my desk, I use some Vienna Waltz wall mounts. They are typically a home theater speaker but produce a nice clear sound. They need a sub. I don't use a sub at work with the radials. I tried a few of the box desktops mentioned but was never impressed. In my opinion, the desk should sound like the main rig, just smaller and more localized. Both these options have that affect.
these PSB speakers have been my go to computer speaker for a couple years, there's a matching sub available as well. I have the sub as well and its perfect for a computer system and near field listening. They have great dispersion as well. quite small as well for the sound you get out of them.
Have you considered a headphone system? An AudioQuest USB DAC/headphone amp is affordable and sounds amazing with every model of Focal, Fostex, and Sennheiser headphones I've listened through. You'll get more bang for buck and can put it all in the drawer when you're done or take it all with you.
But to answer your question, I've honestly never heard affordable speakers that sounded good except DIY home built speakers. If you're willing to build the speakers yourself then you can get both good sounding and affordable. I feel that the closer I get to the speakers the easier it is to hear that they are cheap. By building them yourself you are cutting out a lot of hungry mouths such as the speaker builder, the parent corporation, the distributer, the showroom overhead and the sales person and they will be affordable.
Best of luck to you!
If you have not tried RAAL SR1a 'earphones' then it is worh trying out. I hate headphones and these are like 2 channel sound. On sale in November.
BTW - putting speakers on a desk is a difficult thing to do. Since it is not an ideal locaction I would consider the AudioEngine line of desktop speakers with the angled stands. No need to spend to much money on something that will really never sound great.
I think some here have overlooked the fact that the OP has an amp and preamp and no need for powered speakers. You might consider the passive version of the Kanto line called the YU Passive 4" or the 5.25".
Their active speakers have gotten some really good reviews and I considered getting them unitl I came across a great deal on something else.
All the best,
I also started with a headphone only desktop solution but realized a need for desktop speakers. I opted for a used pair of LS50s from Accessories4Less. A bit overkill, yes, but I'm loving this solution. Sometime later I supplemented the bass with an inexpensive 8" sub from Emotiva (the Airmotiv SE8). It's a flexible solution as the sub has both low and high-pass filters. This way each component in the system is allowed to perform in it's optimum range of the audio spectrum.