I would put my money on Marantz PM6004. I have auditioned PM6003 quite a number of times and have always liked it. Here's why :
1. Warm & Musical SQ
2. Bass : Tight and not boomy/bloated at all. Mids : Balanced and Vocal presentation is quite balanced. Produces vocal textures quite beautifully. Trebles : Goes high enough but never sounds harsh to the ear.
3. Matched well with different speakers (ones I have tried is Dali, Wharfedale, Cambridge Audio)
4. Would provide you with ample power to drive many common 86-88db sensitive bookshelf speakers.
The topping T20 is good for its own reasons (warm tube like sound, compact size, Price to performance ratio) but why I would not prefer Topping is :
1. Provision of connecting only 1 source at a time.
2. Wattage is limited. At times if one wants to pump up the volume, it produces a limitation. Only 8 watts.
3. As someone already rightly pointed, it has to be paired with relatively high sensitivity speakers.
4. I found the pairing of Topping with Wharfedales 9.1 to be a little weird in terms of Treble. It used to produce sibilant highs which would start producing ear fatigue after some listening.
You can try both with the speakers that you are going to run with the these and make your choice.