EDIT: I struggled much, how to give a good answer to that questions. If you have a better idea, pls go ahead.

Based on your questions I have a certain feeling that you have only few experience, but are full of (potentially wrong) expectations.

You should better ask in a recording forum what
- makes a good song or
- makes a song sounding good.
Because there is more required / behind it than simply the selection of the recording interface.

Quickly to your basically 3 questions:
to 1 - Compare quality of songs ? For what purpose ?
to 2 - Do you assume that "good song / sound" is more or less based on a recording interface ?
to 3 - Do you know the "shit in shit out" rule ? There is much truth behind it.

An RME interface for sure will give you a value in terms of quality (drivers, software, tools, handling/workflow, etc).

But the basement for "good sound" is 1st of all, that
- the performance is good
- the room acoustic is well / optimized
- you choose proper Micro for the different vocals / instruments
- micro placement is good
- every single track is recorded well
- arrangement is good
If you do vocal recordings, then also the singer needs to know how to sing into a mic.
Of course also mix and master have to be done well and there many things can go wrong.

So .. you need much experience in many different fields to get something out in very good quality.

There is not much merit in comparing the final products (songs) to rate the recording interfaces based on that.
It will not tell you what you can get out of an RME recording interface, as good sound depends on many things
and is also formed much in the mixing and mastering phase.

The final songs quality is the sum of many different challenges and efforts in the recording and production process.
The recording interface supports you during this process, but is no guarantee, that the result is superb.

There are also differences whether you produce pop/rock or classics.

So where is the merit to compare end products based on RME gear ? There will be songs which you like, some other which you do not like ... But most likely because of arrangement, style, mix and master.

And at the end nobody will be able to say, this song has been produced with RME equipment, I can hear it.

If you want to know whether you took the right decision to get an RME UCX, then simply get it and use it in your own rooms.
You will be amazed about it and TotalMix etc, but please take the time and also watch the TotalMix tutorial videos.

It takes a little time to "digest" all the information, but is worth it, here a collection of Videos and an example how to use it (available in DE and EN):
http://www.tonstudio-forum.de/blog/inde … al-Videos/

http://www.tonstudio-forum.de/blog/inde … teps-DE-E/

Summary: yes its important to get a good reliable recording interface, but there might be other things which you also need to address as well, to make best use of it and to get the quality you are looking for.

What do you mean by this ? And btw he is looking for the UCX.

Ramses, Cyrano and Raphie,...first of all, thank you so much guys. I am very happy that this forum has active users who I can learn from. I am not a sound engineer. I am from a different field of work and as I said I do this for fun, and to motivate my son to learn music and recording as he grows up. But I always wished I had taken audio production courses before I started recording with my crappy M-Audio interfaces. If I did I would have saved so much of my time. I am a fan of math metal, djent and anything that is electro metal music e.g. Celldweller, Periphery. But what I care about now is making high quality 'demo' songs. If I reach a point where I'm confident the song is going to be a good one then I will definitely book a professional studio for pro recording.

The problem with cheap interfaces and equipment was that they killed the joy and creativity in me. Limitations in quality recording will not let you improve your skills. You end up being fed up and disappointed.

Previous to my two M-Audio interfaces I used SoundBlaster Audigy2 PCI card. That was way better than my M-Audio interfaces. I still have it in an old PC in my mom's house. But now, even if I make a good quality ambient and atmospheric piece I will be overjoyed.

I know that UFX series are better products but my budget is below that.To upgrade my home studio I am going to buy the following:

- RME UCX (previously I was going for Focusrite Clarrete series but people changed my mind)
- Blue Spark mic (I am also considering buying a portable acoustic booth)
- DynAudio Lyd5 or maybe Adam monitors, but definitely not KRK. (also considering better room treatment)
- Peavey 50 watt amplifier. This one will be a lot of challenge to record from at home. I was considering building a soundproof box so that I can place the amplifier inside it. I don't want my neighbours to knock on my door all the time. In addition, that will need a SM57 as well, correct? I already have many guitars and effects but I always used direct connection to my interfaces or used Guitar Rig 3. For bass guitar I still have no plans on buying a bass amp.
- Radial's J48 DI box. Let me know if I need this one at all when recording with UCX?

Thanks again guys
-

Hi Ramses, thank you so much. I looked at it. It's affordable although I believe the price was for one unit only. I read some comparisons between KS Digital and other products on GearSlutz. KS products had shown better results. They say they are more revealing.

MixBusTV (Rock Star Recording) Claims to run 2 9652s with SSL Front Ends