[starbux48]

I keep looking and looking.  Something for nothing.  Of course it doesn't exist.  The Topping TP30 looks ideal for my budget but it only outputs 10w into 8ohm and 15w into 4 ohm.  Can anyone recommend any speakers (like Polk) that this will power?  Not to high volume levels either.  Need ideally one unit to take USB output from Mac, have a headphone jack (ideally 1/4", but can use adapter to 1/8"), and drive couple speakers.  If I can find some well-priced speakers, the Topping TP30 looks like its in my budget.

 

[PleasantSounds]

That's indeed a rare combination. Are there any particular reasons you need it all in one box?
The more common setup wold be a DAC/headphone amp with line outs - from there you could use either active speakers or a power amp and passive speakers of your choice.

 

[starbux48]

Just need to keep costs at minimum.  

 

[PleasantSounds]

There's plenty of excellent 2nd hand equipment available that you can get for next to nothing. 
If you find the combo you are after, chances are that it won't be priced to your liking or the quality will leave much to be desired. My advice would be to stick to the main stream where vendor competition is stronger, and you'll end up much happier with your purchases.

 

[c00lkatz]

Ever consider an AV receiver? Good sound quality, tons of connectivity, can be had pretty cheap depending on what you get and what you're looking at, and will power low/medium impedance headphones with ease along with a decent set of speakers as well.
 
Not a common suggestion around here, but it's an option. I've got a Yamaha HTR-6030 and Denon AVR-1712 that actually worked pretty good to power my DT990 250-ohm with good sound quality and got them decently loud, and obviously plenty of power for a set of speakers. Though I opted for a compact desktop setup for obvious reasons and left the receivers to control my home theater. But if you're on a budget, you can get one pretty cheap, especially with them coming out with new models every year with minimal changes, leaving the current or last year's models' prices to be cut in half or more.

 

[starbux48]

I've decided to go slightly different direction.  Checked my local Craigslist and there are some nice Denon and Yamaha amps/receivers with plenty of power @$75 so will look for a USB Dac that just does that alone, not worrying about an amp as that will be taken care of.  If I can go that high, will get the Music Streamer II from HRT.  They run generally as low as $140 with USB in and dual-RCA analog out.  Cheaper still is the FiiO E10 or one of their USB Dacs.  Don't have to have headphone amp either by buying the Denon/Yamahas.
 
Let's change thread if you read this to just look at USB Dacs.  Only remaining question is Async or Adaptive for USB Dac types.  HRT designed theirs as Asynchronous to reduce jitter I believe, but other Dacs also get very good reviews that are what I think are called Adaptive USB.

 

[PleasantSounds]

For a full explanation you can follow the link below, but in short if you have a choice go for Async. In the Async mode it's the DAC controlling the data transmission, and timing of signal conversion is fixed at the prescribed frequency. Adaptive mode means that the DAC needs to adjust the timing to the actual data rate which is controlled by the PC - that may result in jitter.
 
http://www.pearlaudiovideo.com/blog/expertise/computer-audio/usb-asychronous-vs-usb-adaptive/