Looking for advice on a headphone-only desktop dac/amp

Hello friends,
I am new and looking for advice as the title suggests. What I currently have is:
1. Source: Gaming computer ASUS ROG GL552VW, 6 years old - this is the main and only source /there is one free USB-A and one HDMI output/;

2. Headphones:
2.1. RØDE NTH-100
Impedance: 32Ω
Sensitivity: 110dB/V
Maximum Input Power: 1700mW, 1% THD @ 1kHz;

2.2. Kotori Audio DAUNTLESS IEM
Impedance: 12.2 Ω @1kHz 100dB;
These two are my first Real headphones and were recommended to me by "the Honest Audiophile" for which I am grateful!

2.3. I have more:
2.3.1 MOONDROP CHU IEM
Impedance: 28Ω±15% (@1kHz)
Sensitivity: 120dB/Vrms (@1kHz);
2.3.2 OnePlus Nord Buds TWS
Bluetooth 5.2, Codecs: AAC, SBC
Driver Sensitivity: 102dB ± 3dB @1kHz;
2.3.3 (Coming soon) TANGZU WAN ER SG IEM
Impedance: 20Ω
Sensitivity: 107dB (@1kHz).
These are for fun, tests, work use (it's dirty).

3. Dac/Amp - Hidizs S9 PRO
ESS9038Q2M DAC
PCM: Up to 32bit768kHz
Native DSD Supports Up to 512
Single-ended 3.5mm + Balanced 2.5mm

4. Speakers - I don't have and I don't plan to have (I live in a panel apartment...).

As you can see above, I'm new to the hobby - first music setup and I don't have a lot of money... The music I listen to is metal and specifically symphonic metal and melodic death metal. It is important for me that the vocals are heard well and I can say that I am sensitive to high frequencies. Almost all the bands I listen to have female lead vocals and some also have male raw (screaming) vocals.

What I'm looking for is a desktop dac/amp with maximum musical quality related to my musical preferences, a neutral and natural sounding device for the money I can spend ~ $300. I know there are not many, but this is what I can allocate as much as possible.

Regarding the "extras":
1. Bluetooth - if there is good, if there is no - good. It is not very important to me, because I do not foresee development (for now) in this direction.
2. Many inputs and outputs - I don't have speakers and I don't think I will. On the computer I have, as I wrote, USB-A and one HDMI output, which I don't know if it is "suitable" for music. I don't plan to connect my TV to the computer for music. I don't have and don't plan to have any other sources of audio content (CD player, music records, etc.);
3. Balanced output - my current headphones do not need this, and in the future I will hardly be able to spend more than $300 on headphones. And for this money, there will hardly be such headphones with such a need...;
4. It is good to have a display, if not - Ok, and I don't need a remote control.
Not that these extras are bad to have, but they are optional in my choice!

"the Honest Audiophile" recommended the following models to me: SMSL AO300, Fiio K11 and Aune X1s GT.

Of the listed, I first settled on the SMSL AO300. Then I read here and there and some more candidates jumped out at me besides the ones I suggested above. Unfortunately, I can only judge devices by other people's reviews and ratings. Here in Bulgaria there is no place to test devices, and I don't know anyone who is passionate about this hobby. In addition, from here (BG) it is not possible what is done as I read on the forums elsewhere - to take devices and if you don't like them, return them...

What came up in my search is:
1. TOPPING DX3 Pro+
2. SMSL DL200
3. FiiO K7/K7BT
4. TOPPING DX5

Yes, the price is important to me, but the quality of the music is more important to me, and from the point of view of perception, not as numbers! As I already wrote, I am looking for a device that reproduces music neutrally and naturally, the music I like as well. Hidizs S9 PRO I will use it with an IEM when I'm not at home, but at home I want a serious device that will give me the necessary musical experience working with my old computer and my available headphones. If there are extras, fine, but they are on the second or third plan.

I'm personally gravitating towards the SMSL DL200 and maybe the FiiO K11, BUT I'm not a reliable arbiter at all, so I'm hoping for some advice from you?


Thanks in advance!